Hm, Austria is fun to play because it's in a central position and often a big challenge. In the majority of games Austria gets eliminated within 2 years, and I think I've only played one game with Austria, and I won it. If there was still the View History button I could recall what I did... but here are some general tips.
Diplomacy is perhaps most critical for Austria seeing as it will border and compete with 4 other countries within the first year (only Germany has the same situation, but more guaranteed SC's).
Of course, the first thing to point out is that an Austro-Turkish alliance is near impossible. Taking into account that both players are not entirely altruistic and that they plan on winning and not lying over on their side for their ally to rampage around, Turkey and Austria cannot co-operate in the long term. IF they do, Austria will obviously come out ahead, since they have more room to expand, Turkey will find themselves stagnating, and will notice soon that they HAVE to attack Austria in order to have any reasonable hope of winning, short of running up into Russia, around into Germany, and France, all the while Austria sits idle? (Nah).
So what about Russia? Russia and Austria CAN co-operate, especially against Turkey at the beginning, since it's in Austria's best interests to get Turkey off the board, and in Russia's best interests to remove Turkey early if he wants to pursue a northern campaign. Of course the most dangerous position for Austria is a Russo-Turkish alliance, and although unlikely, this should be Austria's #1 priority. Because if they have an alliance, Austria is as doomed as a vegetarian jaguar. Galicia is the key territory for this relationship, and an organized bounce or some sort of demilitarization may be necessary around this area to assure trust. Also, negotiation of the division of the Slavic countries and Turkey is not easy, and should be worked out for a practical alliance.
Now, Germany. Germany perhaps is Austria's most natural friend. They have some fairly annoying null territories between them that make war between them in the early game quite unfruitful and more likely to benefit the other countries. Above all, Germany and Austria cannot afford to stagnate or they will find themselves surrounded and overwhelmed. Together, Germany and Austria have a lot of purchasing power, and a lot of strategies to insure a peaceful Italy involve Germany telling Italy to back off, or they will enforce rule from Tyrolia. Of course, the obvious target of this alliance is Russia, and Galician control is crucial, as well as making sure Germany isn't being harassed from the west too much, and Austria from Turkey in the south.
Finally, Italy. In so many games I see here, it seems that Italy and Austria immediately duke it out. This is most likely because it's such a tempting proposition, especially for Italy. An Italian stab against an unsuspecting Austria is by far the Fastest way for an Italian player to expand in the early game. On the other hand, a competent and prepared Austrian player will almost always win against Italy in the end. If you are playing Austria, point this out to Italy, and if you still don't trust him, leave an army back to discourage a quickie in Autumn. Venice-Trieste and the Adriatic Sea are obviously the key points of the conflict and they have the only two adjacent home SC's which make for some interesting diplomacy, and continual paranoia. Besides these problems, if you make sure Italy knows that you are prepared to crush them, perhaps with German help, they will usually listen if they are reasonable (or have a SURE alliance with Russia and/or Turkey, in which case be afraid). One of the most classic strategies is the Lepanto, which usually involves a very lucrative alliance between these two countries, and an early defeat of Turkey. I'll go into more detail in my next post.
So there you go, those are some general strategies. Remember to be diplomatically active, people tend to ally more with those who communicate well. Also, since you are in the centre, you can't stop expanding. If you start to stagnate, you will find your hands full with a growing France/England and a rampaging Turkey/Russia. Stuck between two superpowers is a horrible place to be. You want to dominate by mid-game, and be in the position where attacking you will be so unattractive that people will go out of their way to keep the peace.
I hope this helps with Austria. Remember to think like other players, and think about what THEY want. Everyone's playing to win, and since allied victories are not enabled, assume that no alliance will carry through to the very end. Cheers!