Okay, so in the demo,
1) do not ally with anyone,
2) send a relations expert to the Malmuks and Austria,
3) build carracks like crazy in Venezia (discounted price), build troops as possible (carracks first always, have one queued).
Your timeline is basically thus, Austria will go to war with Flanders, the Ottomans shouldn't declare war so long as you do not go to war (which you will have to do if you ally); at least they didn't on me the couple of times I tried this. Kind of try to watch the Flanders situation, as much as you can, if you get the sense Austria is soon to close out the war, call your diplomat back and then make an Alliance with Austria as soon as they make peace with Flanders because their next target is you. By this time depending on events you get, well, I've had around 21-22 military (3/2 in favour of infantry over cav) and 4-5 Carracks. It's not enough if the Ottos declare war on you, but you are close, so there is a small period when you are vulnerable because the Austrians won't really help very much against the Ottos. If enough time has elapsed you may be able to get the Mams on your side, I didn't really need them because I managed to blockade the straight in my one game before the Ottos could get their big armies across.
Basically you have to pull a page from the Byzantium box to start the game but you just have more money to pull it all off.
Anyway, that's my advice. In this short 50 year demo you kind of have to bend over for Austria.
1) do not ally with anyone,
2) send a relations expert to the Malmuks and Austria,
3) build carracks like crazy in Venezia (discounted price), build troops as possible (carracks first always, have one queued).
Your timeline is basically thus, Austria will go to war with Flanders, the Ottomans shouldn't declare war so long as you do not go to war (which you will have to do if you ally); at least they didn't on me the couple of times I tried this. Kind of try to watch the Flanders situation, as much as you can, if you get the sense Austria is soon to close out the war, call your diplomat back and then make an Alliance with Austria as soon as they make peace with Flanders because their next target is you. By this time depending on events you get, well, I've had around 21-22 military (3/2 in favour of infantry over cav) and 4-5 Carracks. It's not enough if the Ottos declare war on you, but you are close, so there is a small period when you are vulnerable because the Austrians won't really help very much against the Ottos. If enough time has elapsed you may be able to get the Mams on your side, I didn't really need them because I managed to blockade the straight in my one game before the Ottos could get their big armies across.
Basically you have to pull a page from the Byzantium box to start the game but you just have more money to pull it all off.
Anyway, that's my advice. In this short 50 year demo you kind of have to bend over for Austria.