Practice, practice, practice and practice. That's the most important thing I guess. But some random things from my experience with the weapon:
-It depends a bit on the stage, but one thing I tend to do is to stay in the middle of the stage when we're in the lead and pick off anyone who tried to break through. Musselforge, MakoMart and especially Sturgeon are great stages to do this. The latter is probably my favorite Range Blaster stage, actually.
-Try going after people who are trying to stay hidden or who flee from you. The range combined with the blast-radius makes for a great weapon to hit people who think they are safe but aren't.
-I generally tend to play kind of aggresively but not really at the very front-lines. If that makes any sense. The Range Blaster fires kind of slowly and missing a shot up close means it'll either hit a wall of explode relatively far away from your opponent. But if you're good at playing with it (which just takes practice, really), I think you can pretty safely use it in more close up duels. That's also probably why it's my favorite Blaster. You have a pretty good range to harrass people or protect some kind of middle point, but as long as you're good with your aim, you can still take people out reliably from up-close.
