"there is nothing new under the sun" and "good artists copy great artists steal"
Browse the web for inspirational websites like :
http://www.fromupnorth.com/ or
http://abduzeedo.com/. save all the designs you like and mix them.
Choose object from one of them, pattern from the other, style of the third, composition of forth..etc.. and create your own design. It will be unique because your own style will add to that. and .. try to make it better
Create flow charts: Sun - light- bright - energy - happiness - smile ..Your thought process will take you places you never expected.
Create fake customer in your head. Thing about what he want. What is the purpose of the design? Who supposed to like it? What kind of message supposed to be behind it? What kind of feeling its suppose to create? Excitement? Happiness? Happiness – energy – bright- Sun. Maybe Sun in a good idea for the main theme? There is a cool sun picture in your saved files. Looks awesome but it would be better with style from the other one.
Doodle. On paper and digitally. Open Photoshop, create a rectangle, copy it 10 times, move them around, skew them, play with filters , textures, blending mode etc. 9 on 10 results will suck but one on the will be interesting. Remember how you did it and use it later on. You will create your own style and eventually there will have no time to put all ideas in your head into action
Remember that this is a marathon, not a sprint
Good Luck