I guess it depends on your past experience and your design. No problem with either colour when I've used them. Make sure you do the red first, make sure it's dense enough, either back with a normal red and then white for a more intense colour or back with white, then do the yellow, again make sure it's dense enough and back with white.
Yellow is a bit of a pig to work with, make sure your brush is washed out well and not likely to spit any contaminants into it, likewise make sure your work area is as clean and free from stuff the air can blow about as possible. Otherwise it will end up in the yellow, and yellow shows up everything
Aside that I can't see you having any problems.
Make sure you post up your work so we can all see what you do !