Hey, I understand what everyone's saying, it maybe worth just brainstorming and sketching as many ideas as you can for a week or so. Whilst playing with dreamweaver and css, php, etc at the same time. This way you'll start creating design's that are more complex than your first, but your not too scared to try them.
I love creating new sites now, I learn something new (at the moment several new things) everytime and it wicked. Each time my designs and layouts improve, because I have a greater understand of what I can achieve, what can be achieved, and what would be awesome if I just knew how! The only problem is it makes all my previous sites worse and worse! But hey it's all experience eh?