I usually set a formation that count my opponent formation.
If I don't know how he is playing (this period for example, where oppo players don't have contracts and you can see weird formations), I prefer to set 4-5-1 V, def/counter/flanks and 2 blue arrows in my DC, two red arrows in my wingers.
If I 'm not satisfied from the game, I change to normal or attack.
If my oppo playing from the middle (without wingers or ML-MR) I use 3DC + 1DMC, 2 MC, 2wingers and 2 ST.
I use DR/DC and DL/DC so to make my defense narrow or wide, also use DC/DMC so if my oppo set 3ST, to put him back as third DC.
If I see that my oppo has only one DC then I use 2ST or maybe go from the middle, with 2 ST and one AMC.
normal tackling
passes, depending (if oppo has DM, not long)
zone/man to man depending
* if you see the board of a match (with the rates), then you can recognize what are the formations of the teams - but of course you don't know the orders.