Question about tiling...please help

[rav055]

I am getting ready to lay new tile in my bathroom. I took up the old ceramic tile and am leaving the underlayment as is. it is pretty level. It has some spots that can be filled in with thinset, but my biggest concer is that there are some spots that are higher up where the grout was. I plan on getting a chisel and hammer and just knocking them out.

Will this work ok?

 

[gcol]

If on a wooden floor, try a heavy duty scraper. Screed floor, use your chisel.