If you are interested in learning how to play bluesy sounding riffs, here's a great beginning guitar lesson. It is real simple to play as the teacher goes through 3 mini riffs step by step and then combines those 3 into a larger riff.
It took me about 10 minutes to figure out how to play all 3 and then get the combination right. In the video from YouTube.com, the guy plays it slow and then kind of shreds it up really fast. I can't play it that fast at this point, but he stresses that if you practice, practice, practice you will get faster. And that is the ticket, don't try to shred right off the bat and don't get bored with your practice. I recently cam across a video where this musician is talking about a hit guitar instrumental song that he wrote and he had to practice that song for 1,000 hours before he was comfortable playing it live. And this was for a 2 minute and 30 second song.
If professionals still practice that long, us beginners haven't even gotten started yet. So check out the video below, work it out and practice, practice, practice.