Lardar pretty much summed up the best approaches, but to make a correct plan we'd have to know just what level you are. Oh, and OSRS gold good luck! It depends exactly how you wish to do it, personally, I despise runecrafting and don't require the cash, so I slay always at the minute for effigies to use on runecrafting, as well as helping people with their RC effigies, (91 onwards, I'd recommend this as it's a totally free 30k rc XP per day) I'd use the penguins as well for a fast boost once a week, as that all accumulates well to a top XP count in as long as it will take for 99 Runecrafting.
Apart from, less or more what Lardar said:Nats via abyss. ZMI Altar. Alternatively, when free trade comes back we should see the growth of Air, Law and Double character running again, and that might be a preferable method, to sit at the altar all day and have people bring essence to you.
I'm thinking of camping avies soon.my stats are 73 range/80 def/60 pray. Should I use tank method? If so what should I use? Should I just wear my present range armour? (complete armadyl, snakskin boots, zamorak blessed dhide vamps, ava's accumelatour, ammy of rangeing, rune cbow, broad bolts, god publication. The Granite protect works nicely as it has a very high ranged defense... or if I just wear monk robes and RuneScape gold buy higher prayer bonus and pray all the time?