Flooring Tile - Help laying Travertine tiles!

I’m getting ready to lay some 12”x12” travertine tiles on a bathroom floor and I had a couple questions. First, I’ve received some conflicting information on how much thinset to lay them in, one recommendation was to use a ¼” trowel, but when I went to the hardware store, they said to use a ½” trowel and special Marble & Granite thinset that had thicker granules or something for more support. Then I was told to use 3/8” grout lines with sanded grout, but again, at the hardware store, they said 1/16” to 1/8” grout lines with un-sanded grout? The thinner grout lines seem to make sense since the tiles are machine cut and quite square, although it seems I’d be losing some of my ability to offset any errors I end up with by making the grout line thinner or thicker, but ½” of thinset seems like a lot, and I’m worried I’m not going to be able to get them all level.

Take the time to get your floor real flat before you tile. Use a medium bed thinset like Mapei ultracontact. 1/4" x 3/8" notch trowl should be good . Smaller grout lines look best 1/16". Take your time and get all the tiles on plane. Any lippage will show on this type stone.