For your convince here is a link to all the levels I made in the past:

http://www.jazz2online.com/downloads/search/bjarni/

I don't need to know why these levels are bad, I already know why they were bad. However, what I need is advice on how I can make better levels.

I know one thing I did terribly wrong back when I was a kid/teenager, in the hard difficulty the levels are overcrowded with enemies. It won't happen when I get back to level making. But what else?

Bjarni isn't my name on Jazz2Online anymore, it's now Blaze The Movie Fan, which is my Internet name everywhere.

When I return to level making (which I will eventually) I will go back to this thread and read all the constructive criticism. Again, I don't want just reasons why my old levels were bad, I also wanna know how I can improve and make better levels.