I noticed a lot of "how do i custom tile set" threads, and thought this might be helpful.
it is a Paint.net file that contains everything needed for making tile sets easy.
everything is in layers which can be hidden when saving final tile set.
Layers:
1. dot guide
2. blank
3. smb tiles (for reference)
4. grid
5-8. backgrounds for transparency testing
http://www.mediafire.com/download.php?aeldxo50bxhpsqh