I do have a reflow oven (the old PCB-Pool mini oven "convertible"), but I realized that it has one big disadvantage when soldering prototype boards: I cannot access them while reflowing. As I find this possibility very handy to fix a tombstoned part or to check correct floating of a QFN chip, I came up with another solution.
Here is the complete process in a series of pictures, plus a video. The board shown is the battery management system as part of my current project
https://www.eevblog.com/forum/projects/introducing-my-project-'kicksurfer'/msg1170253/#msg1170253.
Preparing a fixture for solder paste application
Aligning the stencil, fixing it with tape
Inspection of correct alignment, pushing down the stencil
Using leaded solder paste for my prototypes, that just makes the process easier; store in refrigerator, let it warm up and thoroughly stir before use
Applying a blob of paste - note the board added to the right, which is to support the stencil and keep it from flexing in the next step
Spreading the paste, the right angle is important, move slowly, distribute pressure evenly, go all the way in one pass without stopping
Finished spreading
Stencil removed - be careful here as well, move slowly but steadily
Close inspection of critical structures - this is a 0.4mm pitch QFN
Preparing component placement
Placement - my hands are not too steady (you'll see that in the video), so I use my other hand for stabilization, creating sort of a bipod
Fully populated board, not all components are spot on but that can be fixed during soldering
Video showing the reflow process in our kitchen. I did some tests with an infrared thermometer before, in order to find the right power setting. It's a pity that it is limited to single-sided boards
https://youtu.be/hptbgbDvaskFinished board!