Changing formations to much will make ur players lose morale faster, try to pick one formation per season and build ur team based on that formation.

Some of my favorite formations are....
3-5-2
4-3-2-1


The blue arrows are for defending, so u can use the blue arrows for defense and the red arrows are for attacking so u can use those for offense but I suggest you don't because those arrows narrow down ur players options and often make u lose games.