I am tiling my bathroom floor and putting in a new shower base. What do i do first? Do I put tiles on the whole floor and then but the base over it? or put the base and then put the tiles to it?
You should put tub and tile backer board down on the floor where the shower will be and then once the tub is installed tile up to the edge. You dont want tile underneath as it may or may not end up level, it may or may not come loose after weight is put onto it, and most importantly grout is not waterproof...it will absorb water and you definitely dont want that under the shower.
Basically if you want to do it the easiest way and right - the shower base or tub is the second thing installed in a bathroom. The first being the basic framing for the bathroom.
Exit plumbing, thinset under base (for some), whatever you need to do get the base/tub set up in stone. The next steps include prepping the rest of the floor for the tile and tiling. The only time that this would differ is if you were doing a clawfoot tub.