Most Helpful Girl
Go to places like Big and Tall and Old Navy. They tend to carry larger sizes for taller, broader men. There is nothing wrong with being bigger, but I can understand your frustration. I am full figured and have a hard time finding tops that fit my boobs and pants that don't let half my butt hang out.
Try to find stores that sell things that fit you, try on different styles. I think that a nice dressy button up shirt over jeans is a good look for most guys. Maybe add a nice watch, too. Get a good pair of shoes, some nice pants and some good tops that fit well. Maybe even some shorts that fit well too. I think the best thing to looking good is to just get clothing that fits well.