I have not done very much (about 3 small circuit boards). What worked for me was having a nice soldering station, really fine solder, a magnifying light a pair of fine plastic twezers and liquid flux.
I could usually put some flux down on the pads, position the component and try to heat up one pin and it usually will suck the solder in. On some components, I would try to get a little solder on one pad, position the component with the tweezers and with the other hand try to heat up the solder on the one pin to tack the piece in place and then solder in the other pins. When I created shorts, I would use one of those vacuum suckers to try to remove it and other times I would use some of that braided desolder wire. When I finished soldering the board I would try to clean up parts of the board with alcohal to remove the flux.
As I said though I have only done three small boards. There are probably several people who know much better ways than this.
I use Johns aproach as far as using the X-Acto knife to hold the part in place, but I use normal (thin) solder and a very fine tip soldering iron. My method requires a helper to hold the part, but it goes very fast.
Having been in rework for 3 years at my company, I would use a slanted coined tip and lots of solder flux. First I place the component on the pads and using tweezers, align all pins to the middle of the pads for all four sides of a qfp as an example, and then apply flux to one corner pin, then without touching the pin, place a ball of flux on the soldering iron tip and bring it to the pin to tack it. there should be no physical contact, just the solder ball. its likely there will be a bridge but that’s ok for now.
Next tack the opposite corner the same way. After the part is square and tacked, I flux all pins on one side and lay a sthort length of thin soder across several pins, around 10 pins, and then touch the tip of the soldering iron at a 45deg angle on top of the solder. Instantly the pins will absorb the solder. There will be bridges, but if you glide the tip back and forth over all the pins, the solder evens out removing any bridges. If to much solder remains and there are still bridges, you can clean off the tip, add more flux over the bridged pins, and touch the solder with the tip and the excess will pull on to the tip. This process may have to be repeated until the bridge is removed. Another option is to use a solder wick.
The method I use works well but only with a small bent coined tip. Tips that are staight with a fine point will not work with this method, and I find these tips tend to overheat and have poor heat transfer characteristics.
This is just how I do it. It depends on the equipment used. I wish I had a way to make a video showing how this it done. Perhaps the safest way is one pin at a time for starters.
At my work, we used SN96 solder 95% of the time and some SN63 as well as HMP solders.
My user name is SN96 for this reason. Its been 2 years since I did any rework, I now program machines.
when it gets much below 0.039" pitch or 0603 parts I take it downstairs at lunchtime and have one of the girls do it… usually costs me a trip to the pizza place or something to get them lunch but when I get back my board is all built.
seriously though, , doing it myself I usually resort to the 4x lens/lamp and putting small amount of solder on 1 pad, holding the iron on the solder so it is melted, and I slide the part into place with tweezers. if it is an IC I’ll secure the other end in similar manner so the part can’t move around and is aligned properly. then I solder the other end/pins by heating the pad and bridging the pad to the leg using solder until it melts. flux helps.
I think I will use regular solder, it seems to work fairly well. I might try SN96. It seems to have a very high melting point? I don’t think I’ll use solder paste, it seems like too much work. Might be good to try though if regular soldering doesn’t work too well.
Any RoHS (Restriction Of Hazardous Substances - in the USA pronounced ROE-Hoss) solder is going to have a higher melting point, just need to make sure you use RoHS parts to take the extra heat, else component damage can occur.
Solder paste is hard to work with using an iron and generally only used for convection reflow.
My motors arrived yesterday! They are so powerful and small!
I have almost finished designing the motor mount and I will start building it Wednesday or Thursday. Winter break in three days so I’ll have lots of time to work on it. Late start Wednesday too so I’ll probably finish the design.
I have a prototype of the PCB printed and assembled, and have tested most of the functionality. Made a couple mistakes on the routing (mainly to do with the programming header).
I am hoping to start making my wheels today or tomorrow but I have this project on the back burner for a while as I am starting a tube amp project. 8) (Stereo 6V6, single ended triode, with 6sn7 input and 5y3 regulator tubes for anyone interested)
The wheels will be somewhere around 1 inch but I want to find the best size for my motors. I already have the round stock I need. It might be 6061 Al but I didn’t check.
, doing it myself I usually resort to the 4x lens/lamp and putting small amount of solder on 1 pad, holding the iron on the solder so it is melted, and I slide the part into place with tweezers. if it is an IC I’ll secure the other end in similar manner so the part can’t move around and is aligned properly. then I solder the other end/pins by heating the pad and bridging the pad to the leg using solder until it melts. flux helps. 
Might be good to try though if regular soldering doesn’t work too well.