Hi Karen! Man, your question can have so many “correct” responses because choices about artist tools is so dependent upon personal choices and intentions. That caveat out of the way I’ll share with you a general kit I recommend when I teach watercolor to those new to the media.
First off, I tend to advise tube paint over dry. There are, in fact, some excellent quality dry paints…but there are so many more terrible ones. Even student grade tube paint will result in more intense color than a mediocre dry kit.
Invest your money in fewer brushes, but higher quality. One or two good rounds, or one round and a flat will get you through a lot. I have a very nice number 12 round that I use for 98% of my studio work and a similar size in my travel brush. I ask my students to get a number 8 (the larger size tends to intimidate them, even though both will make equally super thin lines with a bit of practice.) Water brushes are convenient and I like them too. They’re also cheap. But they are nowhere near as versatile.
For transparent watercolor I advise my students to start with a palette of seven colors, made up of a warm and cool triad, and one neutralizing color. This might look like Ultramarine, Cad Red Light, Quin Gold, (warm triad); Cobalt Blue or Cerulean, Lemon Yellow Pale, Alizarin (cool triad); and Winsor Green (used to neutralize the reds and for mixing grays). I also like Perylene Green as well as a couple other colors for my own palette – colors I use to replace others from time to time. What sometimes looks like a bargain, but may not be, are the kits with basic colors selected for you. Usually those are more difficult to create color harmonies with.
One final thought about color – and trust me when I say I could go on MUCH longer! – consider using a limited palette. A well chosen triad and one neutralizer will teach you way more about mixing and representing color in a much shorter time than a kit of twenty four pigments will.