this guide is by all means incomplete. It rather points out possibilities than an optimized strategy.
Austria starts as a comparatively strong regional power and rarely fails to become a major power in any game because of its inheritances of Burgundy, Bohemia and Hungary, in rare cases even Spain. So you could basically sit idle for the first 100 years or so till you inherit Bohemia in the late 1520s(?) and Hungary in 1540. But of course you shouldn't. Peaceful expansion (diplo-annexation) into german territory is one option, keeping France out of Italy another. The italian provinces are quite valuable (Venice and Genoa are CoTs too and you don't have one - however, both are tricky to force-vassalize as they own islands and you don't have a fleet or even a port) and if you wait long enough all of them will even have a manufactory of one kind or another. However, Spain may have interests there too and a war against papal states, as always, is not advisable. If you are lucky you will inherit Milan (Lombardia), often along with Mantua, or get them as vassals by event.
You should choose your allies as fits best your current plans, having them declare war for you. Papal states are an excellent option, sooner or later they will DoW venice and other italian states, same goes for Milan or Mantua. Spain (Castile) is a strong ally that helps protect from France and with which you have no "conflict of interest". Bohemia and Hungary are options, you may want to prevent them from turning against you.
In mid-game your opponents wil be the Ottomans and usually France (unless you helped keep them small). Poland usually makes fair game if its not allied with Lithuania (or wait till they self-destruct) as it is plagued with negative scripted events. Keeping the ottomans at bay should not prove difficult, depending on how well hungary did before you inherit them. Expansion in the south-east is generally not worthwile as most provinces there are poor and do not match your culture and religion.
If all goes well you have plenty options, the only upcoming/remaining threat being Russia.