I do like to document the process when I make new figures, so please find below two guides.
One for how to make a simple one part mold and the other a two part mold, enjoy!:

Tessetoys Guide 1 : A simple one part mold
Tessetoys Guide 2 : A two part mold (how I made Oakor)

Other very handy guides :

Dan Perez Studios – Workshop
molding / casting tutorials and some sculpting tips

Hirstarts Mold Making
how to make simple silicone and latex molds

James Rogers Sculptures Studio
figure molding, check how they make the air canals into the mold

MyHeap Molding and Casting Resource
process of making molds, casting up to things like making milk plastic

Jumping Brain – flickr sets
flickr prototyping photosets from emilio garcias jumping brain

B9RobotResource – Molding
silicone rubber mold making – how-to guide

Paint-Sculpt – Mold Making Tutorial
mold making step by step

Alumilite – How to
all kind of mold rubber & cast resin video tutorials

Freeman – Mold Making Videos
silicone rubber and urethane casting resin video tutorials

TAP Plastic – YouTube Chanel
video tutorials about their own rubber products

Pity Mold Suply – YouTube Channel
different techniques and sfx related molding video tutorials