Depends on your goals, timeline and budget.
I'm a 02 rookie and in the same boat as you. My 2.0 engine (attached to front sub frame and trans) is out and on the garage floor. I have a notional plan which includes most of the items below that will kick off once my home paint job is complete.
My Moto: Embrace the mission creep - plan for it to drive another 50 years!
That said and excluding all the things that you can do to the engine and/or engine swaps, here are some ideas (most of which you can do with the engine in as well). It's certainly not exhaustive but food for thought.
Clean everything
Paint engine bay
Powder coat or chrome plate as desired
Inspect repair or replace heater box / hoses
Inspect repair or replace steering box
Inspect repair or replace suspension
Consider an Alternator upgrade
Consider E30 M3 Starter
Consider new carb options or FI options
Consider 5spd upgrade
Inspect repair or replace wiper motor
Inspect repair or replace Washer fluid reservoir, pump and hoses
Inspect repair or replace hood hardware/pads bump stop thingys (Anything rubber)
Consider upgrading your pedal box and Brake booster to 2002
If your sticking with the 1600 Booster (tuna can thingy) Linwar motors in southport England has em
Run new brake lines (Single or dual circuit)
Replace MC
If you are upgrade to a 2002 booster consider having it rebuilt (IE or 2002AD and others do this)
Replace the Sound barrier (Just bought one from Blunt)
Replace rubber elephant trunk drains (not sure what they are called)
Make provisions for a trunk based battery
Consider installing A/C system (Yeah - I'm thinking about it)
Test electrical / overhaul and Re-wrap
Inspect repair or replace grounds
If you dropped your sub frame - re-enforce engine mounts (IE has the plates or make your own)
Consider replace front sub frame hardware (I just bought some pretty new hardware from WN
Overhaul struts/paint
ETc...
Basic engine items:
all new belts,
hoses,
water pump,
thermostat,
various gaskets,
motor mounts,
trans mount,
clamps,
oil,
antifreeze,
oil filter,
and misc hardware (Alt bush etc...).
Good Luck...let me know if you think of anything else - I'll may add it to my list.