Pregnant: How to prepare for breastfeeding

Last month, I received this message on my Facebook page:

I am pregnant with my second baby and really want to successfully breastfeed him coz I failed the first time. Im still on my 17th week though but if I can do something as early as now to prepare myself for that, I'd gladly do so. What can you suggest?

I've been receiving similar concerns via email and private message so I decided to compile some tips which I hope will be useful not only to new moms, but also to moms new to breastfeeding.