The ‘Horizonte’ Hat could be a good project to practice stranded color-work. It uses a simple color design. I used a 9 inch (16cm) long circular needle to knit in the round the whole project; because this is the method that I like the most, but you are free to use any technique of your preference.
Mainly, you will be working with 2 color yarns on the color-work section, except, in one row, that you will be combining 3 colors at once. Take into consideration that the central part of the hat, where the color-work is, will be less stretchy (almost none) while you are making the adjustment for your own size.