Casting on with 2 colors to make one row

I have been knitting for years and I know or thought I knew that to cast on and join 2 colors should just be to take the 1st color and twist that around the second color and then keep going in that pattern. It is not working. I cannot got a smooth cast on row.
Help, I have tried 3 times and I know this is a simple task. Jill

Here’s one way of doing it. See if you like it.