I started out sewing clothes...didn't really get into quilting until about 7 years ago.
I'd start out with simple patterns...I agree with bearisgray on sewing lounge pants or pajama bottoms where the fit is looser. When you want to try something more, McCall's and Simplicity patterns both have lines that are marked for easy sewing...You will even find patterns marked "Sewing for Dummies" that are full of diagrams and easy-to-follow directions....and YES! Take your measurements! Like others who have replied...patterns and ready-made clothing don't run the same...Good luck and happy sewing!