Re: Tinting paint?
Like has already been stated, stick with like paints...same gloss, same brands...
If you add blue, it will get more purple...if you add brown to the purple, it will turn more maroon...I use the finger paint test method to mix colors...get a white piece of cardboard, dip your finger in the red and smear it on the cardboard, then using one of your tinting colors begin adding some to the red, continue until you get the desired color...if you don't get the look you want start over and add a different second, third, etc color to the red...this will give you a basic understanding of what colors do to each other and an idea of the amounts required to achieve the results, then scale it up...
Do you have MS Paint on your computer?
If yes, click on it and look at the upper corner where the colors are...there is a box that says Edit Colors...click on it and you can play with color shading, it will also give you a fairly good representation of the percentage values used to achieve your desired color choice...
