Austrian Strategy
Targets:
These are the centers you're hoping to get. As you know, eighteen are needed to win. The essentials are your home centers, the Turkish home centers, and the Balkan centers. You're not going to be able to win with a live power in your back, so the Balkans and Turkey must go. From there, you have some options... Munich pretty much always goes to you, so add that and you have 11. From there, you have to consider whether your primary ally is Italy or Russia. If Italy, then you add Berlin and the Russian home centers (minus St. Petersburg) for fifteen. If Russia, you add the Italian centers and Tunisia for fifteen. From there you can pick up eighteen, either by picking off the home centers of your primary ally or by pushing further from your initial borders.
Essentials: Vie, Bud, Tri, Ser, Gre, Bul, Rum, Con, Ank, Smy (10)
Pro-Italy: Mun, Ber, War, Mos, Sev, StP, Kie, Hol, Ven, Rom, Nap, Tun (12)
Pro-Russia: Mun, Ven, Rom, Nap, Tun, Mar, Spa, Por, War, Mos, Sev, StP, Ber (13)
Grab the essentials for sure, and then pick eight from one of the last two lists depending on how your alliances look.
Openings:
Austria has a lot, but there are only two that are really worth mentioning: the Galician Balkan Gambit and the Southern Hedgehog. The Galician Balkan Gambit is your ideal opening and requires you to be certain of peace with Italy. Italy can either run a Lepanto or attack France. If you're strong diplomatically and you can successfully play Russia and Turkey off of each other, you want Italy going after France so he doesn't get in the way and claim centers you'll eventually need to win. If you're not certain you can play them off each other, though -- or worse, if you're sure THEY'RE allied -- then you need Italy to run a Lepanto to counterbalance them. The Galician Balkan Gambit orders A Vie -> Gal, A Bud -> Ser, F Tri -> Alb. You'll want to arrange a bounce in Galicia with Russia; this will keep him from putting another army on Rumania, giving you an easier time getting it for yourself, and it will keep your army in Vienna so that you can deter any delayed Italian backstabs. The other two units can virtually guarantee Greece. If Italy stabs you're still in a decent position; move Vienna to Trieste, take Greece, build as much as you can and defend from Italy while you recruit help from France with Italy and try to get an ally out of Russia or Turkey. If Italy doesn't stab, you can move to Galicia again and take Greece, get two builds and get to work on Russia or Turkey (or both, if you're clever).
If you're not sure of Italy, you play the Southern Hedgehog: A Vie -> Gal, A Bud -> Ser, F Tri -> Ven. Announce both the Galicia and Venice moves to Russia and Italy, respectively, and request bounces. The moves are defensive and meant to deter the infamous Russian-Italian alliance against Austria and do a pretty good job of it, while ensuring a build from Serbia. The idea is that Italy gets stood out of Venice when he moves Rome there, so the one army in Venice is stuck and not able to fight you effectively. Italy is told all of this before the first phase, and asked to run a Lepanto because he can't profit from attacking Austria. You arrange for him to move A Rom -> Ven, A Ven -> Apu and F Nap -> ION so he can convoy to Tunisia as in a standard Lepanto, without being in Venice in the fall. Then in the fall you move F Tri -> Alb to set up for Greece; A Vie -> Gal again to keep Russia out; and, most importantly, A Ser -> Bul. This gives Greece to Turkey (A Bul -> Gre), but stands him out of Bulgaria (A Con -> Bul), isolating Greece and leaving you in position to take Greece, force a disband of the Turkish army in Greece in S02, and possibly even support yourself into Bulgaria in A02.
There are some minor openings -- different variations of the Balkan Gambit that send Vienna elsewhere, basically. None of them are as good. Some of them cover Tyrolia or Trieste, but this is defeating the point. The Balkan Gambit is used because you trust Italy not to attack you. Thus you're throwing your forces at unknowns in Russia and Turkey. To compromise that effort by sending a unit as insurance to defend against someone you trust is not wise. If you don't trust Italy then one army going after him that ALSO fails to defend against Russia is not going to save you, and you need to run the Southern Hedgehog anyway.
Powers:
England -- Your best friend in the west. England and Germany both struggle to project significant force into the Mediterranean; England can very rarely get beyond Tunisia. And England also doesn't have the opening to launch an attack against the Russian centers beyond St. Petersburg in force. England also needs the German centers to win, like you do, but you have a significant advantage in getting to them. So England is rarely a direct threat to your soloing chances. This is in stark contrast to France, who can push into Italy easily and block your chance to win, or Germany, whose very EXISTENCE is a block to your chance to win. But England also has the ability to harass France, Germany, and Russia, the powers you need checked to win.
France -- Not very useful to you. France is really only useful as a counter to Italian aggression (in which case you have to make the best of a bad hand -- sacrifice your claim to Italy in exchange for not being outright killed) and a distraction for Italy and Germany. Franco-Italian wars are good for you, especially if France also gets attacked by Germany and is competent enough to handle both of them. That leaves them more vulnerable to your stab.
Germany -- A short-term good friend, long-term nuisance. Germany needs to be encouraged to go west, and needs to be a counterbalance against Russia. He can keep France tied up and out of the Mediterranean, and keep Russia tied up and out of your hands. Preferably Germany is moderately competent but not superbly good; it'll eventually be competition for Warsaw and Moscow, and you'll need Berlin and Munich to win, so long-term Germany isn't your best ally.
Italy -- Depending on your diplomatic capabilities, you want him to go west if you can handle juggling Russia and Turkey, and east against Turkey if you cannot. He will be the straw that breaks your back if Russia and Turkey ally, but if they're looking allied you can probably talk him out of attacking. After all, you have enough trouble juggling Russia and Turkey; how much harder will it be for Italy, once Russia and Turkey have both grown strong through alliance with each other over your corpse? It takes a VERY good Italy to manage the kind of diplomacy that would make an attack on you work, so luckily most Italian players can be dissuaded from that attack. Long-term... you'll have to kill him (or nearly so) to win, and he'll have to kill you, but if you do some good diplomatic work then you can postpone that war as long as possible. Generally speaking, the later in the game an Austro-Italian war is, the more successful it is for Austria. So work with him very closely early and keep him busy against France (and, if you must, Turkey), and stab him when you have a clear opening (ideally a turn where you get two builds, and he has no garrison or builds; you don't always get that chance, but if you do, you can easily walk into Venice and Rome and end his winning chances).
Russia -- Useful against Turkey. You want him working with you against Turkey early. Get him to build southern fleets as much as possible: they're useless in defense of his home. Keep them bottled up in the Black Sea area and they're useless in general. You'll probably want to look for the opening to stab him before Turkey fully dies.
Turkey -- The Enemy, generally speaking. Austria and Turkey CAN ally, and I would look to this as a backup alliance option if Russia proves incompetent or insolent. But ideally you'll want to be working with Russia because you can at least have a CHANCE to attack him later. Once Turkey gets out of its hole it is virtually impossible to destroy because you have no way of attacking him, no one to ask to help. Russia has a northern front that can be shellacked, at least, so Russia's preferred. Turkey needs to be dealt with, ASAP.
Strategy:
Get Italy onside ASAP and weigh your options with Russia and Turkey. Prefer allying with Russia over Turkey if you have to, but don't be afraid to change alliances frequently. Your goal is to get all four Balkan centers however you can, initially. You have to do some talking and play the beginning by ear to see how to advance, but you're looking to get Russia and Turkey embroiled in war. Bring in Italy if you have to; otherwise, get him going west. Once you've beaten Turkey down adequately, decide with which of Russia or Italy you want to continue being allies, and figure out how to stab the other one quickly. If it's Italy, make your move and throw everything you can at Italy to get through him quickly, and send a unit or two north to get Munich with Russian help. Russia is going to be pushing west now, so you have to get through Italy quickly and start pressuring the western edge of the Mediterranean. Once you've secured the Mediterranean for yourself, start looking for the opening to make a game-winning stab against Russia. If you decide to ally with Italy, look for your opening to KO Russia as soon as you can and secure the entire southeastern and eastern corners of the map for yourself. You then want to move quickly into Germany; while Italy is still your ally, the rest of the powers are less inclined to gang up on you because they have to account for Italy. So push into Germany and get some more centers, then make your move into Italy for the win.
Other:
Gunboat notes -- ALWAYS play the Southern Hedgehog. Read the situation from there; you tend to want to follow the strategy outlined above, with Italy as your long-term ally, but you have to read the orders carefully to see if Italy will reciprocate. Look to get beyond the stalemate line as early as you can afford it in all cases, but especially gunboat; it's harder to set up a stalemate line, which means that if you can get a few centers behind the major line, you can hold them for quite a while.