Wet and Dry - How do you use it?

Just one of those questions really, plenty of people ask and I'm sure that the use and way I have used it over the years may differ from others. I generally buy a mix grit pack, coarse, medium and fine like this: 10pc Wet and Dry. It's a cheap pack but it does the jobs and I would certainly not pay 50p a sheet!

If working on metal (after heavy preparation because it will not shift a great deal of rust in my opinion) I will use a rough grit. Plenty of elbow grease later a medium grit followed by a quick fine grit. Then I wet the paper (water but you can use a variety of lubricants) and by using circular motions it will 'blend' in the scratch marks left by other abrasives. Heavily wet the paper and surface several times to get a really smooth finish. Allow to dry fully and it's ready for prime and top coat. If I'm filling a rust hole I will repeat the 'fine' part above, again both in wet and dry forms to blend the filler in with what is left of the metal.

I have also used wet and dry abrasive paper in its dry form on things like MDF, both in the home and model making. I find that it will give a mirror finish to these types of non grain woods or even plastics such as acrylic. It is, for me, a less 'harsh' sanding experience than using sand (glass) paper. Just my thoughts, let me know how you use it and what other ways you have found to use this type of abrasive paper.