The why and how you win games is something that will take some time to figure out. I have a basic idea of what to look for... but I've only been here for 4 months. I know others that have been here for longer still are confounded by why they win or lose games.
Some basic advice:
1) Get your roster down. 15 is OK... but getting down to 12/13 is optimal.
2) Figure out what you want to train. Remember that training is better for younger players. Also remember that you are going to be training more than one player (you train by positions played in the game).
3) Scheduling a scrimmage every Thursday is critical for training purposes. In order to get fully trained for that week, a player must have at least 48 minutes played in a position that is being trained for the week.
4) Be careful on the transfer list. Especially now... prices are going up as we near the playoffs. Depending on where you are in the standings, it might be best to hold off on buying anyone off the transfer list.
5) Also with that in mind... it isn't necessarily the worst thing to not be promoted to V.4 next season. I had to stay in V.5 this season... but will be much more prepared to actually compete in V.4 next season. If I was promoted after last season... I might be looking at a return trip this year.
If you have any more speciific questions (especially with regards to roster decisions), BB-Mail me.