Like mentioned, a Porter Cable Dual Action polisher is great for beginners. This is what I started out with. Granted you're not gonna be able to remove heavy scratches with it, but it can get mild to minor scratches out. I absolutely love my new Makita 9227C rotary buffer and don't see how I lived without before. It literally cuts the polishing time in half. I finished my Tahoe in about 8 hrs... the paint had a lot of swirls. I just started with my parents Suburban and it's in a lot worse condition than my Tahoe...... my Mom beats the shit out of it
It took a long time on the hood because there were several scratches. I clay barred it and man was it dirty. The rotary ate up the scratches and now it's looking great.
Just make sure you clay bar before you polish.