These are inspired by wallpaper I did earlier today. Could anyone tell me how to improve these?

Add a gradient black to transparent, top to bottom in the image.

i think its a bit to bright. try to use a cool colour.

In my opinion it's just fresh. I like freshness though. Nice set Graphyx!

i think ur right there; it is fresh. it's like fresh fruit salad colour i think.

Cool !
just add a little inner shadow to yellow part inside the border.

Cool!  

That glass frame is really cool you can use white-transparent gradient on the part of the gloss that's over the yellow image and perhaps a rounded glass frame

i agree, a rounded frame is better.

i love it. simple.

great job.