Though having expensive and branded materials will help you paint better, I personally like using cheap materials while practicing watercolor. But if you have the means to purchase those high quality watercolors, watercolor paper and brushes, the better.
So, where to start?
1. Have your materials ready. - watercolor paper, different sizes of brush, watercolor and tissue. You may need pencil and eraser so might as well have those, too.
2. Look for reference. Could be from the internet - there's tons of them or you can take a picture of the sunset, the beach or whatever works for you and use that as your reference.
3. Research. About the different techniques, different types of watercolors and materials to be used. Though you can skip this if you want to start immediately. You can also find tutorials on YouTube to really get inspired.
4. Try it. Remember, your first try won't be perfect. It could be really bad, honestly. Especially if for a first time and that's okay. Don't stress yourself too much. Watercolor skill takes time to develop, unless you are one of those gifted artists who've been born with it.
5. Keep on practicing. It may sound cheesy but practice really makes perfect. You can attempt using different techniques to be able to determine your strength and then, stick with it. Once you've practiced enough, well, practice more. There's no such thing as enough practice, believe me.
Watercolor is not for the impatient. There will be moments when you just want to finish your masterpiece but remember that when necessary, you need to let that watercolor to dry first before adding another layer so DON'T.TOUCH.THAT.PAINTING.JUST.YET.
reference: Draw with Shiba