Criticism of my own writing

As I look back through my old essays that I have wrote for my other English classes, I notice a perpetual pattern of lack of support. I feel that I have good ideas and answer the question or topic at hand completely, but I have very few quotes to support my actual claims. I also notice that I am prone to only one way of citing quotes, which makes it harder for me to actually use quotes in my work. Also many of my sentences are overcomplicated rather than just a simple statement. In this manner I tend to lean towards fallacious arguments that sound convincing, but ultimately fall short.