As Cat said, if your teamquality is superb, you will get promoted to leagues where you'll be facing really strong opponents. I take it easy and buy 4 or 5 stars players just to replace the 3 stars players. My league levels have never been demanding for me and I've been doing just fine.
Also I wake up 20 minutes earlier on week days and try to get a new player during the morning coffee time. This is the time of the day when the token buyers I know about are still sleeping. If I'm lucky and there is someone I like, I usually get him for 1 token. If not, I try the next day.
Today I bought a 5 star young goalkeeper for 1 token, 2 points away from 6 stars, already tested him in the CL and he's a keeper (no pun intended!)