I'm with Quaesitor, drawing on a grid really helps out. I always use a grid when doing iso stuff. Also i'd start off with square/rectangle shapes, like simple-ikea-ish dressers, fridges, night stands etc. Curvilinear and other complex stuff can be daunting to start out with.
I'd definitely take a look at existing iso stuff to get an impression of how other artists might tackle iso stuff.

When you feel comfortable, you could post some screenshots of your iso stuff, i'd be down with doing a drawover if you need help.
