I became interested in genomics towards the end of my time as an undergraduate. Experiments in genomics generally result in the production of incredibly large data-sets that can only really be manipulated and analysed using computational methods. Through a combination of classes, self-teaching and internet forums I have managed to become moderately competent at R, perl and shell scripting. It also really helped to be surrounded by a number of excellent computer scientists during graduate school for those moments when I realized I was above my head.
Mostly it was through necessity. After a short class on perl and R I have had to teach myself many of the skills that I use on a regular basis. Some of this teaching came from books like the O'Reilly series, but the internet has an extensive collection of forums like stackoverflow etc. that can be searched. I think generally I have started with an idea of a test or plot I want to generate and crawled through a variety of these forums until I eventually figured out how to do what I want. It's not always pretty, but has gotten 99% of what I need to do done.
The dynamics of transcription and how it is regulated on a genome-wide basis