I would not recommend using 3 textures, especially if one of them is using alpha, as you are going to start to have performance problems if you do this all over. You really just need to practice and learn. Your goal should be to get a texture that doesn't look tiled. Then where you have to use the one texture in a wide open and visually unbroken space, paint in one of the alternate textures, or use the same texture but scale the UV in the editor.
First goal is to get a texture that looks the least tiled as possible. But think about how the real world looks (even if you aren't making a realistic looking game) there's nowhere, except maybe a desert, where the same texture, identically extended for hundreds of meters. There are subtle color changes, or places where the rock or grass is thinner and the underlying dirt or mud or rock shows through.
With 1 grass, 1 rock, and 1 dirt texture, that were all nicely done, and complimentary to each other, plus the ability to paint vertex color, an experienced world building could paint an entire region of a game to look great. Play around and you'll get the hang of it.