
Originally Posted by
Mugajak
Shy away from sub for leveling unless you're really comfortable with it. Once things outlive your opening FW, you need to do some fancy work (compared to the other specs) to use your cooldowns, since vanishing will reset the mob entirely. Assassination should provide "comfortable" single target with ease, and combat has the best CDs/cleave, although leveling a rogue I had to avoid pulling >1 mob as often as possible (post-87/88; 85/86 were a breeze as they are on everything) - use what you have the weapons for. Don't forget how to sap, blind, and just roll that recup/SnD with deadly momentum. You may need to eat/bandage on occasion but it should be relatively rare.
May check out Shadowpanther's leveling guide to see what he has written for the 85-90 journey; honestly I found the dropoff around 88 to be harder on my rogue than anything else I've leveled yet.
If you're REALLY short on gear, don't forget either the AH or those gear vendors out in each area...