for decent items, i would run instances, the bosses that you kill in them usually drops good items, i've never been alliance so i'm not sure what instance you run at around 17 though, for horde we have wailing caverns
For alliance, it's Dead Mines. For grinding, it's kind of class specific. Just go and try grinding on different things. Find something that is plentiful and that you can kill easilly. As long as it is close to your level, I wouldn't worry about the exact exp per kill.
Loch Modan or Redridge Mountains should be decent, there might be a few quests in Westfall for your level but they're probably chains. Once you're mid-20's Darkshire or whatever should hold you over till almost 30. Also throughout the 20's Wetlands isn't bad. You'll also have Ashenvale and Stonetalon Mountains in 20-30 as well.
I can level my characters somewhat fast, the general rules I've always followed are:
Quest in an area just a level or two under you.
If there are multiple areas for you to level in at your level, do the easy ones in one location first, then head over to the other area and do the same.
Spam your LFG for any Elite quests while working on another quest, so you're not just standing around.
Only run an instance 1-2 times for items, and only if you have quests that can be completed there (unless an item is a SIGNIFICANT improvement).
Avoid "delivery boy" quests that drag on forever, as they're more time-sinks than anything else.
When in a rough spot as for quests that you can complete, grind it out until you can move to another zone or can complete them.
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