Hey Luchke, it's easier for me to give you a suggestion if I see some of the original resources you used to make these photo-manipulation...
Judging by these works I believe that you have some potential, but you need to improve your technique... hope that you have a patience
my first suggestion is that you find photo resources (stocks) with equal and more quality... for a start it will make photo-manipulations easier to do
great place for that is: http://browse.deviantart.com/resources/
- and don't forget to credit authors