So! Came time, this afternoon, to break out those $10 solder stencils I had made to match the prototype boards for the new Gadgets.
A few lessons so far.
Alignment holes are your little friends. Include them, preferably by adding paste-mask layer features to the library component for mounting holes.
The stencil house may assume that you supplied solder-mask artwork, and that it needs to make all the openings slightly undersized. If you didn't allow for this in the artwork, application of a lathe to the alignment pins in your fixture may be called for.
A nice stiff steel stencil works much better than a wibbly-wobbly plastic-film one, though not being able to see through it for initial eyeball alignment (if you didn't include the alignment holes) can be a bit of a nuisance.
A guitar pick does indeed make a good squeegee for small boards.
If your stencil is of the frameless persuasion, and not being held under tension in a proper fixture, you will get more generous solder piles than the thickness of the stencil would imply. I think using the paste straight from the refrigerator, instead of letting it warm up to room temperature, might help with this. Making the openings significantly undersized (e.g., with the restring settings in EAGLE) may be in order.
No-clean paste flux plus hot water and dishwashing detergent equals horrible nasty sticky mess. Use alcohol for cleanup - it's not just for rocket fuel any more!
And now it's time to put the paste back in the vegetable drawer (yeah, I should probably have a dorm refrigerator in the lab for storing solder, adhesives, and suchlike) and break out the parts box and the teeny-tiny tweezers. Which it's time to degauss again.
Oh, and keeping the solder-pasted boards under some sort of cover in between parts-placing sessions (for those of us without tireless pick & place robots) should help exclude cat hair, not to mention inquisitive household livestock.