Pingly, that's a separate thread, I think.
Picking out a palette is sort of a separate skill to colouring with one. Using a palette with colours you didn't pick yourself will make you better at seeing in hues, but you'll get a better underlying knowledge of colour harmony if you mix your own palettes. If you want to level in both directions, you should learn to do both. Look at other people's palettes, try to imitate their methods, pick them apart, mix similar palletes to vary effects. There's not anything wrong with using other people's palettes, it really depends what you want.
Off topic, but I'm usually a sticker for spelling, and I've been spelling palette wrong ('pallete') for ages... I'm trying to fix it, but even now I hardly even notice it. I don't seriously think there are other people here cringing at this, but in my capacity as a dude who is passionate about colours and words, it is my secret shame.