If you have NEVER done anything related to player killing, I recommend you start off with a f2p range/2h pure so you can get the basics down before you try to mix in spec weapons and prayers.
A good baseline for a f2p pure is 40 attack / 70 strength / 1 def / 70-80 range. Prioritize having a higher range level than strength level and work on your weapon switching so you can "stack" your hits (two hits in one tick). Theres plenty of youtube videos showing this off.
Once you get comfortable with your timings, you can move to p2p and try out obby maul + range or gmaul + range. Pure melee kind of sucks at lower levels and most maxed pures will stomp you because they have been pking for years.
Best of luck!