Hi :-)
I usually use a cup or a plate of tap water with a drop of dishwashing fluid added. And of course a newspaper underneath to soak up the water. Put a plastic bag underneath the paper to protect the table. When you are done for the day, fold up the paper and put it in the bag. Presto: neat and quick cleanup.
When you fold sandpaper, fold it so that you avoid grit against grit.
Pencil erasers make good sanding blocks, they can also be cut to fit a surface/edge.
Rub two pieces of sandpaper against eachother to make a finer grit on the paper.
Good luck, Henrik