Use a 360 degree laser level to mark a line for laying the tiles.
How to tile a bathtub if wall is not level.
With a 3 16 v notched trowel spread mastic just under the laser line and down the side of the tub wall to a small area.
The way i would approach this would be to get your top row correct and level then work down to the floor.
In your case make the top edge level and do your cuts at the bottom whether or not you use base or cove at the bottom.
Spread thinset mortar on the bottom center of the wall.
If so adjust your layout to have wider tile on the sides.
Use a trowel to spread an even layer of thinset behind.
Take a 4 foot level and place it across all the studs.
Do this vertically horizontally and diagonally.
If the studs aren t plumb and level the waterproofing won t be either.
For the vertical layout begin your pattern at the top of the wall so there ll be full uncut tile at the top.
Add a little bit of water at a time to the dry mix to get the right consistency.
Once you are ready to lay the tile start at the corner with the chair rail border image 2.
Spread the mortar with the flat edge of the trowel then groove.
What is wet shimming.
Check shower stud walls.
Mix thinset or mastic to the consistency of mashed potatoes.
When you have studs and shower walls that aren t flat you can improve the flatness before you ever set tile.
Check if you need to adjust this mark to avoid laying slivers of tile at the top and bottom.
However depending on how much of the wall you choose to tile and factoring in a 10 percent surplus incase of breakages a new set of tiles can become expensive.
Laying new wall tiles in a bathroom is one of the best ways to update this space.
The other alternative is to run the wall tile doewn behind the floor tile with a 90 degree corner there.
Divide the dimension in half and make a mark there.
Use tile spacers if necessary to keep the tile lines straight in the layout.