I can attest to Rit Dyes being pretty great for dyeing. I use the Taupe, Brown and a few muted colors to overdyed colors I get in monthly groups that I’m not thrilled with the colors. I did do quite a bit of mottled dying too with them.
I found the easiest way to get something really colorful was to cover and old table I had in a huge plastic bag… then wet the fabric and plop it right on the bag. It keeps it wet and you can move your color around and get it to blend and merge better because it’s wet. YouTube videos help a TON!! Good luck, have fun, and remember you can alway dunk it in brown if ya hate it!! 😆