Sparkfun flashlight kit tutorial web page - explore the different sections on the right-hand side of the page.

Adafruit soldering tutorial video
Adafruit desoldering tutorial video

Soldering is Easy comic by Altman, Nordgren, and Keyser

Plusivo soldering kit manual

Adafruit soldering preparation page
Adafruit good solder joint page
Adafruit common soldering problems page
Seeed Studio common soldering problems page - note that nearly every picture on this page has been copied from some other website. Nevertheless, it is a useful collection.

Sparkfun soldering tutorial web page

MightyOhm Geiger Counter web page

MightyOhm assembly instructions
MightyOhm Geiger counter schematic diagram
MightyOhm Geiger counter photo

1 GΩ resistor photo
Tape the 1 GΩ resistor to your Geiger counter board so that, as shown in the photo above, one lead protrudes from below up through the “TP2 HV+” test point connection, and the other lead rests on the edge of the circuit board. Solder the protruding lead to the TP2 HV+ pad, let the connection cool, then remove the tape.