first: everything you will fit will depend on your skills. when you have better skills then you will be able to fit your bot more efficiently and of cource everything will run better.
get yourself a assault bot asap... light bots are not realy good in killing npcs...
what you need first: extentions that you can fit everything correctly. so cpu and reactor will be your first problem.
second you will need to be accu stable so your guns and your reps will keep running. this is not eve and in most cases you will not be able to just activate your armor rep and let it keep running. thats why most ppl tank npcs by range (what is a bit harder for blue bots at the beginning).
what you need:
high slots:
1x sensor amplifier
rest damage tunings
maybe range extenders if you want to tank on range (mostly with mechs ... needs too much fitting for smaller bots)
med slots:
em guns (forget about the missile slots)
low slots:
variant 1: armor tank: (slow)
1x armor repairer
hardener depending on npcs
armor plate (for more hitpoints, but makes you slow)
variant 2: range tank: (speed)
1x armor repper
lightweight frame (makes you faster but lowers your hitpoints)
hardener
(maybe accu extender if you have problems and the room to fit it, what you most likely will not have)
that should be enough for the beginning.
if you have problems with your fittings:
t1 = standard stuff
t2 = same stats as t1 but lighter (makes you faster), less fiiting requirements (reactor, cpu), and less accu
t3,t4 = better stuff, harder to fit, more accu