I like the choice of colours for the harlequins, but they are
very messy. I know they are fiddly models to paint, but take bit more care with your paint placement and they will look a heck of a lot better
(White is also one of the hardest colours to get right; it requires many, many thinned down coats of paint to make it look even remotely correct... i'd leave it for a bit if i were you)
The Kroot look a lot better

Try picking out some of the details (eyes, claws) to practise painting fiddly things