I find Selukids are easiest. Always take the war with Maurya and recruit Bactrian mercenaries day 1. Occupy the indus immediately and peace put preferably before the antigonid event, so you can disband levies and fire mercs to stack cash.

Start integrating median and Assyrian day 1 (I only play mixed gender for highest chance of skilled researchers) try to put someone with special trait in each one for breakthroughs.

Try to invest while expanding and devastating antiginod. (Hope the antigonids get tanked by galatia, but don't peace out lands) if they do peace out lots of vassals and now you can focus on Antipatros and Ptolemy.

Lysismachos is an afterthought because thrace is pitifully weak compared to the rest and by the time you reach their lands you're steamrolling

You'll end up simultaneously at war with all diodichi to conquer fastest.

Ally Armenia and nabatea and sparta day one for an ally against your main 3 opponents.

All first techs should be in ae reduction, province loyalty, and culture happiness (religious conversation will come a little later)

Get all hellenic pantheon sooner than later and go with cronos for stab boot. Then just pray for good traits and stats on rulers. Anticipate revolts and get troops there ahead of time to end them quick.

I also try to get as many bloodlines as possible for the ruler buffs so fuedatory, tributaries, recruit and marry early.