I started with White Nights and I think they are good for a beginning set – they have strong pigment, re-wet easily and though they are more opaque than some of the more expensive brands, many colors are transparent. If you have these, you have a set good enough to begin with. Buying more paint won’t help you learn what colors you like and need. In the long run, ‘brand’ isn’t the most important thing.
What you need to do is decide what you want from your paints and then learn which colors will give it to you.
I just did a review on Van Gogh paints that you might want to read – not so much to learn about the paints, but to see how I chose 24 colors out of 40 to be my ‘dream’ palette. It might give you some ideas on ways to choose your own.
Are you familiar with the concepts of Primaries, Split Primaries, Pigment Index numbers, and triads? If not, learning about these would help you in choosing colors to play with. Nita Leland is the grand mistress of this kind of information. However, some people just prefer to dig in – you have what you need with the White Nights set to do that. Once, you have an idea of the colors you like – not just because the pigment is pretty, but because it has the properties you like, and it works well with the other colors you like.
Somewhere along the line you will need to look up the properties of the paints you like – that’s how you’ll know that you prefer transparency or maybe you like granulation or pigments that are less intense or more intense. Then you can branch out to other brands, but your purchase will have more meaning because you can look for the properties you want and avoid those you don’t.
By the way, just to provide the opposing view, I’ll say that even though tubes are cheaper, I much prefer pans myself. Tubes are so messy, and harder to store, and many tube colors dry too hard or too wet to be good pan paints. And a good pan paint will last a long while. I do have tubes as well. If I find that I really use a ton of a color, I refill my pan from a tube because I go through so much. Generally though, if I can buy a color as a pan, I will.