The web app will be released on friday the 12th of September.
This is allways the best thing to make you a nice starting team before the game is even out.
You can log in to the web app by going to this link: [ Register or Signin to view external links. ]
When you first start you will be greeted with 4 gold packs if you have played the previous fifa, so that should get you a decent amount of players. What i like to do is sell most of the non rares for 500-1k coins and sell my rare players for 2k+ this should usually get you around 5-10k to start a team with.
Now i usually like to pick a league (preferably one of the main leagues) and focus on building a squad around that league (can also make a hybrid) try to look for some players you have good experience with either from the previous fifa or the beta/demo.
Once you are happy with your squad you can now make more money, each day you log into the web app you receive a daily gift for a certain amount of time. (usually till fifa is released) Save up all the money/contracts you get given and sell the players, you can also sign into other EA Origin accounts that you have played fifa on and transfer the players/daily gifts over onto your main account.
Make Sure To Keep All High Rated Players From 84+ As They Will Rise Later In The Week!

Useful links for Fifa 15:
[ Register or Signin to view external links. ]
[ Register or Signin to view external links. ]
[ Register or Signin to view external links. ]