I agree with Mark, and as he says, have some different “correct” responses.
I also say tube over pan too, because you can buy pans and make a small palette (https://doodlewash.com/forums/topic/diy-travel-palettes/) and However, if you want a palette then I am going to suggest one, and from there you can continue to buy and refill pans as you wish. I bought it finally because the pan is a sturdy one, and Sennelier makes great artist grade paint… https://www.dickblick.com/items/01755-0189/ OR try Jenn’s new Schminke palette (not my favorite brand but many swear by them and this is HER palette so it is going to be good! http://justaddwatersilly.com/2018/07/03/2018-schmincke-palette-delivery/
Brushes. I would not spend money on hair brushes if that is your thing unless you can try them out. Some stores let you do that with water… I prefer synthetics (no squirrels dying for my brush hair). I would recommend what I love best (Da Vinci Cosmotop) but suggest you look on this page and read all about brushes… there are several great threads! https://doodlewash.com/forums/forum/share-your-art-tools/
I disagree with Mark on his color choices only because I like transparent paints to begin with (which you can find out on good paint brand websites), so am not a Cadmium or Cobalt fan, though I make an exception for Cobalt Turquoise because sometimes you need THAT color. I agree with learning to mix as a good idea but i did all that many years ago with acrylics (which I started with) and so, I love the convenience of color. My travel palettes reflect that, and I have three that are my regulars, depending on what I am painting — city painted ladies (Victorians) versus a base travel palette versus my Primateks, which I use a lot in mixing.
I see no reason to limit myself to a couple of paints unless I am really trekking, and I don’t. IF you are going to do this, then choose three warm primaries and three cool primaries and a good grey for ease — I am not a QoR fan but I LOVE their Ardoise Grey as it is near to transparent!
When you look at an artist’s palette choices look at what they paint before jumping in… Do they live in the desert or on the ocean or in the city or in the country? https://dkatiepowellart.me/2018/02/10/tools-travel-palette-three/
There are some excellent bloggers here — myself included — and Jennifer (above) and Tonya (ScratchMadeJournal) and Sandra (LifeImatateDoodles) and others — they write succinctly about why they like this or that.