General Method Description

Air orbs are used to make air battlestaves; this gives very fast Crafting XP, so the orbs are always in high demand. They are made by taking them to the air obelisk located in low level Wilderness; it is accessed by running all the way through the Edgeville Dungeon. The spell requires level 60 Magic and uses 3 cosmic runes and 30 air runes per orb (the air staff negates the need for the air runes, however.)

Air orbs are generally the best of the four types to make, for several reasons. First, they give more XP. Second, they are often in high demand because they give the most XP when used in Crafting. And finally, the air obelisk is the fastest one to access, and you don't have to dodge poison spiders as you do with the other three. Still, compare this method to charging water, earth or fire orbs, to see which is the most profitable based on prevailing GE prices.

Note that there is no advantage to level 90 skills over level 70 skills here, but at level 96 Summoning you can use a pack yak, which lets you make more orbs per hour.

Finally, remember that even though it takes a long time to do the charging, during which you could effectively multitask, you are in the Wilderness so it is wise to pay attention to what you're doing!