I'd suggest training with Slayer however but you've read all the basics, so that's up to OSRS Gold For Sale you. For recommended equipment, a Black Mask or a Slayer helmet is essential. Beside that, you really just need the whip (or an unruly weapon from Dungeoneerin).
The rest is yours to decide. In the beginning, I'd suggest Torag's legs and plates, they have the best protection-value proportion in game (s'far as I'm aware), black dragonhide for the spell-based missions as well as begin working towards this Recipe for Disaster quest, that gives you the most powerful tools for boosting stats in the game. Also, I'd consider getting an earring with wealth (can't harm), an amulet of glory , and dragon boots - for the latter, if you've got spare change, it's just small strength boost. All in all, the entire thing will cost 2.5-3m.
Combine the two and powerslay! This means you'll use your strongest att/str boosting prayers and super pots to complete your tasks, a cannon is also an option if to/can afford to. This can get you upwards of 100k exp/hr at higher levels, which is as high or higher than armoured zombies and bandits. This also lets you avoid looking like a 138 with a 70 slayers.
Gear to be used is: Barrows gloves, from RFD. Dragon boots. Full slayer helm, black mask until you get it. Use proselyte armor if you are using prayers, and barrows if don't. Whip, try getting a chaotic rapier as soon as you are able to. Dragon defense, antidragon shield for tasks involving dragons (DFS is unnecessary, do not try to use one).
Amulet of glory, attempt to collect an enrage whenever you are able. Ardougne cape 3 or the soulwars cape. While that sounds intriguing however, wouldn't it be a detriment to the purpose of slaying? The fun of getting trained to RS 2007 Items become a Slayer is to learn something new and defeat every challenge, sure good. But why is it not also to earn money? I'm pretty sure that someday prayer potions will increase costs to the point of losing money, would it not?
