You can't expect to just open PS and know what you're doing and create decent things. It takes a long time to understand the program.
Try googling Photoshop sig tutorials and following them step by step. Then, add in some of your own ideas and remember the techniques used. Remember where the tools and filters you need are and what they do.
Sigs are probably the simplest things you can do inside of PS, but that doesn't mean you'll be able to make good ones straight away.
Learn a different technique of rendering (cutting out the images) as yours are very choppy. CS6 has a 'refine edge' button (after you've made a selection it will appear below the 'window' button, to the right of 'file/edit' etc) This makes cutting out difficult things like hair etc MUCH easier than other versions and a lot less fiddly.