There used to be a lot more discussion here, but now there is an official discord where people discuss their teams and the best things to build. https://discord.com/invite/maddenmobile

I try to keep some of this stuff a little more organized with the 'helpful thread' at the top to show what players are available with links to their ratings. Stuart's guides are helpful for the promos; I usually have a link to them in the promo threads.