Doing the little details like the gray on the cockpit hatch and knees and the yellow bits across the suit do a lot to bring out a good look in it. Or at the very least, do some lining on the legs and for the chest vents.
And a word of advice, de-nub your parts before you put it together next time. It'll make the whole thing a lot easier.
And really, the ONLY suits AoZ has kits for are Hazel Custom, Hazel II, Adv Hazel, and Hrairoo. I guess the GM Quel counts, but I always count that as 0083. But for the purpose of AoZ HGUC mix-and-matching it counts.
Hazel Custom is good practice for lining and small detail painting which, not to be a dick, it looks like you could use.
Hrairoo is one of my most favorite designs ever, though, and heartily recommend it to anyone who likes Gaplant.