I am an amateur at best, lol, and have only been doing this for a year or so. But in that time I have soldered over 500 pcb's across 5 designs that I have made. This has been my soldering evolution.
I started out using plain old 63/37 solder, I got one of those magnetic helping hands type boards that have standoffs you can hold a small pcb with. I would take my iron and dab a small amount of solder on each pad of the pcb then place my part with tweezers and apply hot air, the solder would melt and apply a little force with the tweezers and the part goes onto the pcb. This worked really well for 63/37 solder. For smaller foot prints with lots of pins like a tqfp64, I would have to use flux. After doing 25 or so like this I bought a cheap hot plate. The first time I tried the hot plate I thought, "what a waste of money", we'll come back to that. After that I decided I wanted to try solder paste. I got some leaded solder paste and used small dabs on each pad except multi pin foot prints where I made a line and then place all my components with tweezers and used hot air to melt the solder. This method works pretty well with really small part count pcb's. The more components you add the the less efficient this process becomes. Then I designed my next board which has 60 smb components. Still not a lot, but over twice as many as my last board. And I can probably assume my next board will have more. For prototyping I still used the last method as it is very user friendly and if you create solder bridges they are easy to clean up with solder wick. But after prototyping I knew I was going to expand to selling overseas, so I needed to go lead free. At this point I started ordering my pcb's with the ENIG finish and went lead free with my solder paste and solder.
What I quickly learned with unleaded solder paste and big components or multi pin components is that cold joints happen easily with my previous method as the solder needs a much higher temp to melt and solidifies at a higher temp as well. This would create joints where the pin would be on top of the solder instead of in the solder and make debugging circuits a pita. So my next order of pcb's I ordered a stencil with it. OMG, this is so stupid cheap and totally worth the money... Just a note here, make the stencil the size of your pcb and get it sanded or whatever the premium finish is. They end up being around $15, so worth it...
Now I'll move on to the next evolution and the current way I solder pcb's. Back to the hot plate. So now, I get my stencil out and tape my pcb down, and tape the stencil down over the pcb. I smear solder paste over all the pads. I pull the stencil off and wipe it with 99% IPA and a tooth brush. I place the components, put it on the hot plate with a temp of 250°C. Now in a perfect world this would melt the unleaded solder paste I use, however my last pcb design uses 2oz copper plane for the ground on the bottom and some big 2oz pads on the top, but I didn't fill the rest of the top with a 2oz plane, so my pcb warps a bit during the process, this means the edges come up about 1mm and the outer components don't get soldered down at that temp. What I did at first was to take my tweezers and press the board down on the edges and let the paste melt. Now I use my heat gun. Once the bed temp gets to 200°C, I start going over the board with my heat gun, at this point the big 2oz copper plane is already hot so I don't have to worry about cold joints. Once you get the pcb heated up, you are honestly just going over it with the heat gun, it liquifies right away. I will say that if you are using leaded solder paste and 1oz copper pcb's, you can just get away with the hot plate, and it is really cool to watch. Blink and everything is melted.
The next step in my soldering evolution is going to be a reflow oven. I don't know if I am going to build my own or buy one, or even when that will happen, as right now I can prep, paste, get the components on my 60 component board, and solder it in 20 minutes. What I can tell you though, I hate through hole components now. What a time sink they are...