The first thing would be differential gears,(3.73 T5 : 4.10 AOD(E)) and subframe connectors. I would say another good band for the buck mod would be underdrives and a K&N with the silencer removed from the air box. I know it's a big step but heads should be in the beggining of the list. They will make all future mods show up more. Either get some ported E7's or GT40's or if you can afford it some AFR, TFS's.
Also, get some traction. Some good tires, perferable DR's is a good step.
delete A/C, smog pump & power steering
gears (rebuild trac-loc)
subframe connectors
73/76mm C&L air meter
aftermarket headers
offroad h/x pipe
aluminum driveshaft & driveshaft safety loop
1/2" or larger phenolic spacer (cold air=more HP)
cheap aftermarket iron heads ( I happen to have a set of ported Jrs for sale )
aftermarket intake
aluminum underdrive pulleys (not worth it if you removed all unnecessary items mentioned above)
MSD 6 & coil (or equivalent)
quality plug wires (Accel FireWires, LiveWires, Taylor Thundervolt 50s, etc)
hi-vol waterpump
aluminum radiator
flex-a-lite fan w/controller
you can pickup a lot of this stuff used in classified ads or on eBay. Where are you located?? I've got some heads, Hooker headers, 3.55s(NEW), aluminum driveshaft and I may still have a new Metco safety loop. Also have a used 6A.
u want to start with air and fuel, witch u can get form the easy/beginer bolt ons, exhaust, t/b, cai, gears, pullies then u want to do a h/c/i probaly close to each other cause a cam on a stock motor is not doing anything and can loose perf, so i would say start with beginer mods witch really arent going to do much for your perf like drop any secs on quater, but it will help your engine run stronger i guess, and when u get ur h/c/i it will be complete good luck