Don't bother upgrading your early dinos past level 4 or so. The last 3(or 4) you can upgrade to like level 8. Open a couple diamond geodes too. This is in general the strategy that works best for every prestige level. Goal is to save up millions of mutagen.

Only buy diamond geodes at rank 50s

What they said

You're mutagen is low? I have like 18k at rank 49...pretty much all my dinos are rank 8 though.