You might consider hiring a high quality tile cutting unit for the job. It comes fitted with an angle guide for any tricky cuts. I'm sure you'll find it completes much better cuts and is easier to use. Cutting sheets of mosaic tiles is not an easy task, and you might be better off using an angle grinder with a continuous diamond blade.
If the tiles are going over a board product like plaster or cement sheeting, I would recommend something like Davoc SMP Evo.
Add a Stanley Knife for cutting the backing. Tile nippers for any cut outs, especially curves.
My grandfather and father were in the "box of matches double as spacers and put under scribed lines to break tiles" old-school people. Steel rule and a glass cutter for them rather than a dedicated tile cutter.
Using a scribe and snap tile cutter on small hex tiles is going to be clunky by either machine or hand cutting.
The machine uses a wheel to scribe a line, then you lift it up and use the handle to break the tile on the line. The small tiles on a sheet when the Youtube experts cut them have the tiles move around. It does a great job on single larger tiles.
Cutting by hand using a wheel to scribe the line with the rule putting pressure on the tile should hold it in place better, just like the machine it snaps with pressure applied downwards with support under the cut line. If I wanted to be accurate this is how I would do it.
My grandfather would have used nippers lined up by eye backed by years of practice.
Hex tiles normally need to have the interlocking edges cut when finishing the outside edges. You will be well practised in tile cutting once you are finished. - Brad
Make sure your walls are absolutely flat. Mosaics will show every small dip or hump.
You'll need either a wet saw or a manual wheel to cut mosaics. An angle grinder will work also.
You can get twin wheel manual cutters for mosaics from specialty tile shops and they are not expensive, also a pair of tile nips and you'll be good. You'll get a much cleaner cut than with the angle grinder.
Consider some mosaic backer sheets to make life easier.
A 4mm notched trowel for mosaics. you don't want adhesive squeezing out between the tiles.
A cheap mixing paddle is a very valuable tool to have.
Clean all adhesive residue between each tile before it dries as it is very painful to clean once dry. - Vis-á-vis
I don’t think I’ve ever seen any short courses on tiling. I guess this might be due to having to know about waterproofing requirements etc. It’s sort of a trade. Which is not to say you can’t do it yourself, you just need to be aware of requirements. What I do is get the plumber to deal with preparation, and then tile myself. There’s heaps of how to actually tile on YouTube. Also, you can always teach yourself and practice the actual technique of tiling using a sealed piece of MDF. - Mathy