At the very least do PI only in lowsec or lower. Yield and taxes suck in hisec. The ONLY reason for hisec PI is you want to buy P1's and turn them into P2-P4's on your planets, but the money still isn't grand. You can find some better tax rate in lowsec, and if you are in a quiet area you can usually move your stuff around without too much of an issue. If you don't mind moving, join a nullsec group and do PI there and just sell to their buyback. Security is better too. Wormholes with hisec statics are daytripping nightmares and the logistics of moving stuff is a pain. Logistics gets worse as you move up in wormhole world.

Source: Have done PI in pretty much every possible type of system in the game (hisec/lowsec/wormhole c1/wormhole c4/wormhole c5/nullsec and currently run an entire P4 factory in nullsec on 7 accounts).