Oh so you just need to dive on! Yes no need expensive paper but either some that has the side sticked either you need to tense it on a board. If not it'll warp too much. The one with the side sticked will warp a bit anyway so you shouldn't use too much water. If at the end it is warped anyway, you can still spray water on its back, put table paper on and then a board with some weight for a night. Maybe mess with several at the same because you often need to wait for some parts to dry out.

The whole trick with watercolor is to play with the amount of water and how dry the paint is, as it'll mix and blend differently.

Also, for the colour itself, it's good to have quality ones.