Theme and Variations (Development?)

I've been writing a lot of music recently and trying to finish pieces and to fully orchestrate them and to give them a little "oomph". I've run into the problem of having different melodies and different keys and everything has little development. It was suggest to me by my father I look at some of those binary form, renaissance or medieval pieces that have the same moldy twice, and the second time is embellished by the performer. From looking at my own work I have come to the conclusion that I need to work on how I develop ideas/melodies/ etc. I know that symphonies and fugues and different forms of music have a development section but I don't know how to take a melody and elaborate it, take it somewhere. make it more than a radio jiggle. 

Thank!

~Sam

I would follow your father's advice, and take it beyond just binary forms. Study theme and variations, fugues, sonata-allegro movements, passacaglias and chaconnes, etc. Familiarize yourself with the themes and subjects great composers used, and see how they varied transformed them throughout the course of a work. I'm sure there are many resources online that could help you get started.