Combine them and you'll be able to power-up! This means you'll use the most effective att/str boost prayers as well as super pots on your assignments, and you can also use a cannon is also an option if to or are able to OSRS Gold For Sale afford. This could result in up to 100k exp/hour at the higher level, and that's as or more than armoured zombies or bandits. This also lets you avoid looking ridiculous as a 138 with a 70 slayers.
The gear should include: Barrows gloves, from RFD. Dragon boots. Full slayer helm, black mask until you get it. Proselyte armour if you use prayers. Barrows are a good alternative if you don't. Whip, and try to acquire an uncontrollable rapier as fast as you are able to. Dragon protector, antidragon protection for tasks involving dragons (DFS is overkill, don't spend the time on one).
Amulet of glory, try to get the fury whenever you can. Ardougne cape 3 or the soulwars cape. Although it's interesting but wouldn't it defeat the aim of slaying? A big part of training Slayer is learning new ways to defeat every challenge, sure that's great. But isn't it also to make money? I'm pretty sure that someday prayer potions will increase costs to the point of losing money, would it not?
Also, thank you for all the suggestions everyone. Even with prayer potions , one will probably profit from slayer. They are relatively inexpensive. If you only drop them, you could make some money, but If you don't, then buying Slayer Dart's runes from the master of slayers for 35 slayer points (you get 36 points when you complete 2 tasks at Kuradel) gets you about 70k, which is a decent amount and could earn you some decent cash if you put your money into this instead of blocking or cancelling activities.
Is it possible to train on bandits yet, or should i start with Giant spiders within the stronghold until 70 def, then move to Buy OSRS Accounts bandits? Sumona demands 85 combat as well as Smoking Kills that you must complete for slayers who are interested.