Here's what I'd do:
Now, keep in mind, you've got to look at 2 games a day next season, at least until you get knocked out of the Cup by a level 16 team.
(I'm assuming you're out of Champions League now, if not that requires a different approach)
1. Sell off ALL except your 5* and 6* players now. Don't worry about keeping young players at this stage - unless they're picking up a skill point from Cardio alone, they're not going to train fast enough.
2. You're going to in initially need a full squad of 22 to compete in league, CL and Cup at the start of next season, so go look for 4* and 5* free agents. Also HIGH 5* older players 29 old-31 years (do not sign any 32 or 33 year olds) You need good players on the pitch, and you can usually get older players without a bidding war. Also, do your transfer market shopping right after daily maintenance. You need lots of bodies, so you definitely want 1 or 2 token pickups.
3. use your spare time to acquire tokens - watch videos, try your luck at the free offers/surveys (avoid token ads and matomy). Set up a dummy email account to use and never, never, never download and install anything through those offers
Once next season begins you watch the transfer market - you'll only pickup two types of players
a) 5* players who are at the top of their bracket (for me right now 5* is skill levels 30-34, so I only look at level 33 and 34) More expensive is better (faster training) and while you don't need to focus on 18 year olds at this stage, do avoid anyone over 30
b) free agents worth 500k+
As you acquire your 5* players, sell off the old (aged) players. with the fa signings, run them through one cycle of training, apply the skill point, and sell them. This is just a cash-raising business.
At some point after manager level 3 you may be able to start developing younger players who will last 3 or 4 seasons on your team. I don't know where that level is, as i haven't reached it yet.
For reference; in two complete seasons, I'll have two league trophies, and will be in the CL final (hope to win it but will have a tough match). My average player rating is 5* at 33.5, I do not buy tokens.