The best way to get used to your colours is to start with only 3. But the second best way to get used to your colours is to play around with them. Strangely, different colours feel different on your brush. Some are claggier than others,
some require tons of water to dilute, some are super strong straight up. Some are gritty, some are dry, and others are lovely and smooth. But it's not just the feel of the paint that is good to get used to. It's how they play with eachother. How social they are, how they behave on the paper.
So. Pick a colour, any colour. How dark can it go? (without blobbing.)
How light can it go? Is it Granulating?
Staining? Transparent? Opaque? Is it a shooter, or does it just sit there, lazy, on the paper?
Do you think it's warm or cool? Where does it fit in your pallete? How does it mix with your favourite colours (let's face it, you're not going to ditch your faves, just to incorporate some new-comer.) Try it with some harmonious colours, next to it on the colour wheel. Nice? or not. Mix it with a complimentary colour to see if it makes a good grey? Does it dry lighter? or fairly similar. Does the colour hold it's integrity - brightness - saturation - when it dries?
What could you use it for, considering it's properties?
Make some notes in a notebook, recipes, properties, unique qualities...also, if you hated it, that way you won't make that mistake again!!!