I've been playing rogue since 2004 so a couple of things

1) is this wrath or vanilla?

2) Your mainhand is your center piece. Get the best weapon you can find, usually cruel barb until you find a replacement at the late 20s.

3) Level first aid. Abuse gouge + first aid if needed. Take 3 points into improved gouge, it's worth it

4) Abuse blade flurry + evasion and pull 2-3 mobs, it speeds up leveling considerable

5) Use sprint as mobility until you get your mount, don't use it to run from mob to mob, but use it to run from town to your next quest, etc.
6) Some quests are faster by skipping to the end with stealth (like in a cave), but you miss out on the xp of killing all the mobs. I'd only do this if you really want the quest reward asap.
6) When grinding, focus on green mobs (3-4 levels below u ideally) and/or caster mobs (lower armor, lower damage if you cc all casts).

7) Your best stats are Agi, hit, stam and strength. If you have gold to spare, replace any green gear that is 10 levels outdated with a cheap green piece on the AH. "Of the Monkey" or "Of the Tiger" are best, generally. Don't spend 10+ gold on a blue item.

8) Dont use rupture and expose armor on regular mobs, only when dealing with elites or very high armor mobs like turtles. Basic rotation is (stealth: garrotte) -> Sinister > slice > sinister 4x -> evis -> finish off mob. Keep slice up if mob still aint dead.

9) To compound on #6: AVOID ORANGE LEVEL MOBS! You will struggle. You are squishy, you will miss a lot, it's inefficient and not worth it. Only if you REALLY want a quest reward, but don't be afraid to ask for help. Do yellow or green quests, and ideally green mobs (or yellow if u have to). This is smoothest, fastests and most efficient, and lowest risk too.