Watch the 2 Note Hammers & Pull-Offs online guitar lesson by Robert Renman from Blues Booster
Over the years, I've noticed that I automatically developed this hammer-on/pull-off technique, and it's greatly inspired by such players as John Scofield and Scott Henderson. Listen to their legato technique - it's very smooth and their phrasing sound different than alternate pickers. I was never good at alternate picking, but this way I can play reasonably fast and still have good control. I recommend you spend time practicing putting the emphasis (or accent) on picked notes, hammer-on notes and pull-off notes. It's very important to be able to accentuate any note in a lick or line, regardless of technique used.