Ask 10 people and you'll probably get 11 answers, here's my (current) preferred way:
I find buildcraft power (mj) a more useful focus early on, and use that as a power base to then create either solar or thermal eu energy once I have the resources. A steve's carts tree farm is relatively easy to set up and gives you a massive amount of wood and saplings. Simple next step is making some wood into charcoal and using that to first run engines and later run a solid fuel boiler (from railcraft). The saplings can be processed into biofuel using forestry (which Im not real keen on because it requires a specific resource called apatite) or minefactory reloaded (depending if your version of that mod is new enough) which can be used to fuel a liquid fueled boiler. I'll be using the mfr version when ftb updates , until then I just store saplings.
In the latest episode of my FTB beginner's guide I make a tree farm and will start using the wood it produces next episode.