I've learned a lot and enjoyed watching Lady Ada and Collin solder surface mount devices by hand. Using that information, I've taken on a few SMT projects now and am thoroughly enjoying the results. What a huge difference over the through-hole projects I've been doing for the last (ahem) many years.
What troubles me is that it takes good eyesight and a stable hand to accomplish this type of work successfully, two things that are starting to wane for me now that I've been retired for a couple of years. The technique of soldering the first pin while aligning the remainder is working okay for now, but it requires a lot of concentration to get it just right. I've heard of using a bit of poster tack to hold the component, but I didn't have any on-hand to try. Here's how I solved the problem:
1) Use a good LED magnifying lamp with a 3 to 5 diopter lens. The larger the lens the better, especially if you wear glasses.
2) Forget about circuit board vises and such. Put a small, clean scrap of plywood on the table, then tape your PCB to that using painter's tape. I noticed that Collin did this in his SMT video, as well. I use a 6 x 12 x 1/4 -inch scrap of plywood -- it has worked well for all projects so far.
3) Using a small, narrow length of painter's tape, secure half of the component to be soldered, using tweezers to align the component's leads before firmly pressing down the tape. It's pretty easy to get a nearly perfect alignment in this step. Make sure that the tape isn't too close to the component's leads; you don't want to block your view or burn the tape when soldering.
4) With a medium hot soldering iron and a small tip, solder the exposed leads. Use just enough 20mil rosin-core solder to patiently cover each pad and lead, one at a time. If you're careful, you shouldn't have to apply additional flux. I use a Hakko 888D with a TS18-S4 tip set at 600F. To stabilize the soldering iron, rest as much of your hand and arm on the tabletop as is possible.
5) Remove the narrow strip of tape holding the component and finish soldering the remaining leads.
If you're just starting to design and build SMT circuits by hand, choose larger components where possible. I mostly use 1206 resistors, 1210 tantalum capacitors, SMA diodes, and SOIC-8 devices, but have ventured into SOT23-5 and even some 0805 passives with success. I have quite a few more projects in the design phase that will certainly use SMT. Through-hole is great for the breadboard, but I'm completely sold on using SMT now that I know I can successfully and reliably build it by hand.
Oh yeah, the Adafruit ruler (#1554) works great for checking component sizes. Highly recommended.
Again, thanks to Lady Ada, Collin, and especially Trevor and Russ at the local Confluent Maker Space for help and inspiration.