Don't buy any more players until the start of NEXT season.

If you bid for a five star player this season he will be four star on day 1 of next season. You would be better off waiting until day 1 of that season and buying a high 5 star player then.

I'd advise making a decision on what main formation you like to use and making sure that you have players in the right position for that. I look to get as many players as possible that can play at least two positions in the formation I use so cover is easier.

Then I would look at what positions you would need to change formations and look to fill those in next. I stick with a 4-4-2, but like to fall to a 4-4-1-1 away from home from time to time and also carry a player who can play in the DMC role so I can go from a flat 4-4-2 to one with a diamond.

I go for two keepers. Make my main one as strong as possible, with my back up keeper not being a major concern.

I look to have 7 defenders in my team, 2 that are DL+DC, 2 that are DR+DC, 2 that are DC with DCM and a spare that can fill in on two positions so that my back line has plenty of cover.

I then look to have 2 ML and MR's in my team, preferably with them also having AML/R/C abilitys too so I can play a high line with them and then go for at least 3 MC's, 4 if the budget can fall for it.

Up front I aim to have 3 ST's, with a 4th being a ST/AMC

That gives you a squad of 20 (21 if you pick up a fourth MC) which allows you to bring in a player if needed due to injury or if you wish to try another formation. It also allows you to sign any youth players that come to you without having to sell a first team player first.

That is just what I try, it might not work for you, but I find a lot of balance in that.