Roger Bisby (reluctant tiler) gives you his tips learned through hard won experience.
I did not choose to become a tiler. I started out as a plumber, but it wasn’t long before I discovered that tilers and plasterers don’t turn up when they say they will, so I picked up the trowel and learned to do both those jobs myself.
My biggest problem is that I lack speed, which is why I hardly ever bother with rapid set adhesive. It works faster than I do. I also make more mess than professional tilers but I have learned to clean up as I go.
Early on I learned that not all tiles are born equal. Customers may buy bargain lots off the internet or those tile warehouses and they may be ok but they could just as easily be slightly warped rejects which means you are never going to get them flat. They may also be ‘sizy’, which is a trade term meaning inconsistent.
One millimetre is a lot in tiling. If you have a 2mm grout line and the tile is a millimetre smaller or larger than the last one that gap is going to shout at you.
Assuming your tiles are straight and even, you need something equally straight and even to set them on. Nothing on this planet grows that straight so don’t waste your time with lengths of timber.
Even the straight ones are bent so you need to go to your timber merchant and pick up some rips of plywood offcuts from the saw. They will be lying there doing nothing and if you have a sexy smile and a twinkle in your eye they may give them to you. I pay for mine.
Once you set the plywood rips up at the bottom of your first complete run you are in business.
Tilers spend more time setting out where there tiles will start and finish than they do tiling. If you start right you will finish right. The idea is to make the cuts even and easy. No silly slithers.
Tiles are getting larger which means you achieve a lot every time you stick one on the wall but it also means that the wall needs to be flat or you will find out the true meaning of rock and roll. Large tiles also need good adhesive. I like to mix my own adhesive because it has a chemical set 
rather than depending on evaporation.
If you are sticking a large format tile on a wall it can take days for a ready mix tile adhesive to set. The Weber adhesive I use takes around 24 hours to cure which takes the panic out of the job. Always fill the ribs on the back of the tile and use a notched trowel on the adhesive.
If you know how to measure and mark and you have a good cutter you should be able to cut your tiles accurately, but the thing that really shows up the novice is lippy edges. If the edges of the tiles are not perfectly flush it is going to show and the grout won’t save you.
I use the edge of a plastering trowel to straddle the edges of the tiles and also set up a good work light. If I can see light through the gap it means there is still work to be done.
