EDIT: I just hope you arent going to be one of the many lame pures who just say 'I pwn joo' or 'wanna fite let go wildy'. I am just tired of these overconfident pkers, who most the time tele, or are iron pures who have 25 prayer
Ok, Here are a few mage lvling tips.
Buy 1000 mind runes, They are really cheap, and wont cost you more then 12k. Take them and a air staff down to port sarim jail, and head on back to the ol Black night, who is locked up. Coincidentally, he is wearing black armor, which makes him weaker to Magic. So, doing this will get you anywhere from lvl 20-27.
Buy as many chaos as you can buy, They are more expensive but will result in more xp per spell. Now you keep rocking your air staff, and chaos runes(Wind bolt) until lvl 39, Crumble undead comes into play, the best lvling spell besides Hi Alc.
Buy as many air and chaos as you can now, Since you will be using crumble undead, buy a earth staff, and use crumble undead, on any area with more then 3 undead creatures, Whether it be zombies, skells or w/e. Do this until lvl 55 magic.
Buy Or craft nats now, and buy a fire staff, High alc good stuff, like steel plate bodys, rune meds, and yew longs.
Now for ranged, here is what I reccomend.
lvl 1-20, buy every bronze arrow you can afford, and head to any chicken coop. Range here until lvl 20, or 25. Lvl 20-40, Once again, as many bronze arrows as possible, except now you will want to head over behind the crafting guild and kill the cows behind the fence. Do this until lvl 40 or 45. 40-50, Same arrow strategy, Except go up to edgeville in the guard tower and range them, OR just stay at the crafting guild cows, because they are really good xp. 50+ Go near crafting guild and go in the cow pen, and range across the river to the small peninsula that contains the hobgoblins.
These tips may not be the absolute 100% best way to lvl 99 but it is some good info that you should at least check over.