Every project requires a plan of approach or strategy that can include the starting position, what tile material is most suitable, an initial idea about the obstacles and hard-to-reach areas and of course the miscellaneous materials required such as the type of adhesive and grout.
This gives a professional floor tiler not only an idea about how long the work will last but also on how best to tackle certain fiddly bits.
The most important part, as step 0 as it were, to make sure that the surface is level. Any bumps, holes or uneven surfaces need to be corrected before any of the tiling takes place.
Uneven areas can cause the floor tiles to move or even to crack, rendering your investment useless so this is a crucial preparatory step.
Needless to say that the work surface also needs to be solid, clean as well as dry to qualify as a workable condition. Some subfloors or other floor materials need other priming work but your tiler will know how to handle these.