If you’ve ever had any art lessons, you may have been told never to use black for adding darker tones. However, you may not have been told why or what to use instead. I would never recommend that you ban any colour from your palette. If you want to use it, then use it. Black does tend to suck all the light in and create a stark effect. It is a very strong colour, so use it where a strong effect or contrast is wanted.
However, for a more subtle option, there are alternatives to black that you can use instead. If you add a complementary colour to another colour, it will darken it and can be used for much more subtle changes in tone. (What is a complementary colour? See my page colour theory basics for an explanation.)
For example, if you add purple to yellow (its complementary colour), it will darken the yellow. If you add green to red, this will also darken the colour. It also softens the colour, which is something black doesn’t tend to do. Go on try it, you will be surprised by the results. This works for most types of paint.