I'm 38 weeks so I'm not an experienced mum yet, but here's what I've got - some will say this is WAY too much, some will say it's ok, ish... You have to do what's right for you:
Newborn size: 8 bodysuits, 10 sleepsuits, 4 outfits. Some clothing manufacturers build scratch mitts into sleepsuits, so they're integral, like Next. I would guess 6 of the sleepsuits are from Next, via eBay. I then got some others from Asda and the like, and bought a few packets of scratch mitts separately.
0-3 months: I bought pretty much the same amount again for this range, although I might have accidentally bought a few more outfits - leggings and tops, mainly, as I may or may not find it easier to change a pooey baby if I only have to change the bottom half. Who knows. Again, most of it from eBay.
Lots of people say do not bother with outfits for tiny babies. Some folk detest seeing small people in small versions of grown up clothing, so t-shirts with slogans, tiny combats, tiny jeans etc. Lots of people also don't like babies in colours, preferring the simplicity of plain white babygros. Neither of these is right or wrong, particularly, it's personal preference.
One other thing to note is that each retailer follows their own sizing structure. Off the top of my head:
Next newborn: Up to 7.5lbs
M and Co newborn: Up to 7.5lbs
Asda newborn: Up to 9.9lbs
Marks and Spencer newborn: Up to 7.5lbs
Then 0-3 the differences really begin to spread out.
Next, in what can only be a money-making venture, have decided to have Newborn, then Up To 1 Month, then Up To 3 Months, in their sizing structure. Next Up To 3 Months is I think up to 14lbs. Asda's 0-3 goes up to 12lbs on most of their stuff.
I think it's all much of a muchness, but I went for lots of colourful things, as I'm a magpie and love colour, and bought 90% second hand but reasonably new-looking from eBay, so hardly spent a dime. I did buy some nice things new from BHS in their Bambino range, lovely stuff, and from M and Co. Next was too expensive for me.