I have shot some polaroids and I own 3of these sweethearts...
mostly my photos doesn't come out like I planned either. that's pretty much the beauty of it !
I dunno what film you use but
if you use impossibles PXfilm you should cover it from light after taking your photo and put it immediately in a case or something...
first package of b&w film I shot turned out yellowish cause the photo got exposed after it got out..now I have a black sheet taped on my camera so the photo slides under it. after that I put the polaroid in my camerabag and everything turned out 'better'
you might have a different reason why your polaroids turn out like they do. good luck 'n try to figure it out, films kinda expensive nowadays for sure