In reply to Styx:
IMPs - The original micronuts (used to be called RPs) and probably still the best. Definitely get a set of these first.
Peenuts - I like these, they don't go down as small but they are good.
Cams - The only microcams I've really had much faith in are the old Aliens. Good luck finding any for sale though
brass offsets - VERY short lifespan but I do like placing them.
Micro wallnuts - too weak, check the breaking strengths. Also because they are so wide they don't tend to fit as well in small fiddly placements. I had a set once but I dropped a couple, broke one and abandoned the final one on an abseil.
BD c3 cams, wild country zero cams, friend 00, DMM 3cu and 4cu - I don't like any of these in small sizes for various different reasons ranging from too stiff (likely to move in placement when the rope moves) to too flimsy (I just can't trust the ultraflexible things that look more like jewelery) to just not fitting very well in placements. Quite a bit of this is personal preference ofc.
Take what you will