1) We try to find a player 5* (not 3* or 4*), with quality X3, X4 or X8, X9 (Q43, Q54, Q78, Q89 for example).
2) We try to find a player with two positions so we could add one more, but not two
Example > DL-DC so we can add DR > DL-DR-DC. Not a player DR
a MR-AMR , not only MR
a AML-AMC, not only AMC, so we can add AMR > AML-AMC-AMR
3) If we want to add a special ability (or extra position), we must build that first and then increasing the quality (adding sp)
4) We must find a "working" (anyway ), sa like defensive wall or header for defenders, sudden striker is also good, one-to-one sometimes.
Free-kick or corner specialist are too unstable to invest on them.
5)If you cannot afford to have many fast trainers, try to find key players
no GK, it's a "neutral" factor in the team
no defenders, you can find good defenders in the market
no MC. Real good MCs are those with a godd working sa but this is rare
no STs. Lately they have problems in scoring. Only after testing you can invest to them.
the best investment is to find and develop a good winger.
AML-AMR are key players for winning the game.
They are the best scorers.
They earn lot of MoM extra skill points

6)Best to find the fast trainer in the first day of the season (18 y.o.).
After testing him in the cup game and in a friendly game, then power train him (training in 3 bars, practice match. Only him, not together with others(cause of injuries).
Train him for 50-60-70 sp. (use reds for an injury)
Then, let him rest for a couple of days.
The first season you must spend some more greens if you want to add sa or position.
The other seasons, you invest only to increase/keep quality.