Removing tiles

Hi,
I am not experienced in removing tiles or plastering at all, so any advice appreciated. I have started to remove old bathroom tiles and then the cement that was used to hold them in place. Although I am trying to remove the cement as cleanly as possible some divers and holes are being left. Should I fill these in before tiling again? What should I use? Does what I am doing look ok in the photo?
Thanks in advance for any help!

Looks OK the wall is pretty sound, you can go mad and skim it but I would not bother with that one. Just ensure you have no bumps left on the wall I would just apply adhesive the small depressions will fill and provide a good key. Do not copy the last tiler with dabs of adhesive on each tile though apply adhesive to the wall with a notched trowel (a sq metre or so at a time so it doesn't dry out) and fix tiles with a slight twisting motion.

Really appreciate the reply footprints. It is nice to know I’m heading in the right direction! I didn’t think anyone would reply, so cheers again!