If you want a simple but overall nice tileset, for example if its a snow/winter tileset:

1.on the top of the tiles do straight lines like this ________one pixel high, when you finish with that line do the next line a slightly diffirent shade of the same colour and so on.
If you want to make a really good tileset you may very well have to spend lots of time making it and put alot more effort on it.

2.You could use some textures your drawing program (I am not very skilled in this area though so I cant help you with this).
Or you could do every, or most of the pixles in a single tile a diffirent color or shade.

To add a tube, follow 1 for example: start with a very light colour then go to a very dark color then start going lighter again, however it takes alot of colors to do this if you want a good one.

I am no expert at textured backgrounds and I dont rip other other peoples backgrounds or Epics either.