I use Winsor and Newton Artists Quality watercolours. This set is a grade below and quite a lot cheaper. It is a small set, so you can get used to the paints and the way they work and also get used to the idea of mixing.
Also, being a small set, it is great to slip into a pocket and take with you sketching.
I shall be using this set in my videos in the near future so if you want to follow along, I’m putting Amazon links below to the set and the Derwent watwer brushes too.