You should use less vibrant colors so things so blend in so much. It also makes it hard to see for most things. Stay away from the dissolve feature of Photoshop.
Tips: If background is white, don't use light color text, even if it is only a small portion of it is white. (To bypass what I just typed you can make a layer of pure black then lower the opacity of it some so it shades over the background picture but not your text.)
When you are going to put two pictures together you should use the eraser tool and put it on soft brush and erase a bit of the side of one picture so the blend better.
Anyhow keep a good motive and be ready to have to get a learning curve. Good efforts.
When starting off you will have a hard time until you come to the high point of the learning curve and after you get there you will be able to do amazing things and you couldn't believe. You will have ideas come to you like its nothing, and if you cant think of anything just try random things until something clicks in your head.