Nice work for a beginner Bedsy. Here's just a few tips for photoshop based on my limited and completely unqualified point of view.
1. Less is more, don't overcrowd things with special effects if they aren't needed.
2. Be careful when cropping layers. Any white or square edges stand out like a sore thumb. Zoom in heaps and take your time.
3. Sample a sh!tload of fonts to find the most appropriate one. Additionaly be careful with the colour of fonts and make sure they contrast with the background. Also check the box to make the edges smooth. Off memory its under font options or something.
4. Use lens flare sparingly. It's usually not needed.
5. When pasting a cropped layer onto a background. Use the blur tool once or twice. It helps to blend the layers together. Also once your done, i like to flatten the image then blur it again. It's only fractional but makes a big difference to making it look like a single image.
6. Keep a central theme. ie don't use a bunch of different effects which really don't go together.
Good luck. You've actually inspired me to reinstall Photoshop on my PC. I haven't used it in ages but its good fun when you've got nothing to do.