Here's a few tips, right before you fight eat a rocktail so you can more than likely get his hp down before yours, and then you'll be at a decent advantage. Don't forget to bring 2 recoils, one to equip and one to hold until other one breaks. Use a phoenix necklace when you see them pull out a special weapon, just remember to take it off when they're done, and equip your other ammy on (phoenix will more than likely break though). Have your spec weapon at the 2nd to bottom row, somewhere in the middle. How do you know when to spec? I always have my exp counter open, and when i see over 100 xp gained in a hit, and they're hp is low go ahead and click on spec weapon, press f5 and spec away. Remember keep your hp around 400ish, if it gets any lower just eat.
Edit: set quick prayer to melee, so if you get rushed press quick pray and eat.