Not sure if you wanted feedback, but oh well, here goes.
I have two concern regarding your tiles:
First off as Eino says, too many colors are used, this is true for all but the purple set. One would think that using fewer colors is harder, but it actually isn't, (IMO) using less colors makes it easier to change the colors and using less shades makes it easier to see which pixels look off. Its easy to fall in the trap of using many layers and filters to take "shortcuts" in tile development, Its almost impossible to make tiles with too many colors look right. I've spent hours trying to alter the dungeon floor tiles with layers and filters, making the new lair tiles, before scraping everything and starting over.
Second: lack of planning, this applies to 1 and 3 (and maybe 5). I can't really tell what 1 and 3 are supposed to look like. It feels like you started drawing without a concept in mind.
The rest is just polishing.
My favourites of your tiles are:
The blue mosaic.
The Purple floor.
The Portal.
The sand-covered stairs. (after seeing these tiles I tried to make my own version, but I
failed).
Because those has the strongest concepts.
This is the process I usually go through:
1. Think of an Idea of what I'd like to do.
2. Drawing a sketch using two colors.
3. Add more colors and more details.
5. Tweak colors, fix oddities.
6. Make a mockup and fix more if necessary. (this is probably the most time consuming step when making tile-able tiles).
-- off topic --
And lastly, since I'm at it I'd like to mention that I'm a big fan of your vaults, your vaults inspired me to make the few vaults I've made so far. Your latest submission is especially amazing and I can't wait to see it in-game.
Keep it up!