base:
chop:
guys, i'm starting learn these time attack styled-chops i need opinions of what shoud i do to improve my chopping skills

The idea and kit is nice.
here and there bit unclean and rims low quality
skirt and lip are toony
Car is imo little to big in bg.
shadow is to strong, need some work
And u forget the new bg in windows...

at all nice. try to work bit more clean
and use better quality parts

Pretty much what best-design said.

I see most of your selections are very rough, are you using the lasso tool to select or the pen tool? If you're not using the pen tool I think you should start learning it right away, it's a bit tricky at first but it's worth it for those smooth selections.