I want to just quickly show you a little cool technique here, called drop D tuning. All that really means is you're taking your low E string, and you're simply tuning it down to a D. So, what I'll do is I'll quickly match it to the open D string, an octave lower. Wow, I nailed it, first time.
Now, when you're tuning down, it could go out of tune a little bit, so what I like to do is just give the string a couple of tugs, just to make sure it stays in tune. That sounds quite nice and solid.
So now we have a low D instead of a low E, which enables you get more of a lonelier sound. It's a little more haunting, having your guitar tuned down like that. It works great for a kind of a swampy blues thing.
That kind of a vibe. Try exploring different songs with your drop D tuning.