Techniques
Some tips I found useful below. Please get in touch if you would like to share any of your own tips.

Card Techniques
90 Degree Joint, Curved Joint, Concave/Convex Joint, etc.

Plastic Techniques
Sanding & Finishing, Assembly tips, Creating a Bend etc.

Foam Techniques
Cutting, Gluing and Filling, etc.

Basic Electronics
Servo Modification, Soldering & PCB Modification

Tricks of the Trade
Creating Accurate Folds, Hack Saw Vs Razor Saw, etc.

Beta-Techniques
Working with new materials – more techniques to come!