here`s my tips

1 - if not promoted then buy at the of the season as they will be same star/rating for new season so do not buy 5 star player if promoted as they will 4 star for new season

2- unless you have tokens then bid but to a limit you set yourself and watch transfer market of a few player`s to see who is bidding and how crazy it is

3 - is what i do, wait 3/4 day`s then pick up decent player`s as other`s would have spent a lot in the 1st an 2nd day