Slapping wet paper to a board
Instead of tacking watercolor paper to a painting board or similar, a lazy method may be useful, esp. for wet in wet: Just slap the wet paper onto a smooth board or similar, take away the excess water by slightly rubbing a moist sponge over it and start painting.
I use a plastic drawer which has survived some old office furniture (See picture). It is light-weight and has a nice rim around so that the excess water won't drip on the carpet. When the paper finally comes off in the drying process (after 1/2 hour or longer), it tends to dry relatively even. I have heard of someone using a baking tray for the same purpose.