I'm generally following this guide, but doing WMMMP. I also generally try to clear every dungeon at level - not because that's optimal leveling, but its just something I enjoy doing. I always have to learn a few things the hard way myself - which generally gets me back to what the OP had for his level recommendations.

1-12 - Quested in Tirisfal. Went to Org at 13 to pick up the RFC quests. The lieutanant's ensignia that you need in the cave outside Org is one of few quests where the quest item does not drop for the whole party at one time - each slave needs their own kill which was annoying.

13-17 RFC. 13 was doable - but difficult. Mostly a learning experience about how to pull, which to pull, how not to chain pull. Critical note - make sure you have wands before you start. Only had enough mana to burst down 2 1/2 mobs, then all 3 mages were oom. Now that I know what I'm doing, if I level a 2nd group it would have probably been simple enough at 12-13. Back at 14 and with wands - much easier. AOE'able at 16 ( I don't think I had any AOE before 16???). Stopped at 17, exp seemed be slowing. Maybe 6-8 runs total?

18-21 WC. I started at 18 after gathering all quests. Easy enough to just burn down casters from a distance. Weird having my tank doing nothing on most fights. Need to watch mobs that sleep and that run and chain pull. Stopped at 21 to turn in quests - 2 full runs + 3rd partial for more hides. Wiped at least 2x because mobs running off to chain pull while I was oom.

22 - did initial ashenvale quests (bring 5 blunderbus's). Mistakenly thought I needed to do the 16x satyr horns, so ended up grinding out 1 1/2 levels on those - that was a mistake. Note that there's 2 different Satry camps, one had mobs 26-28 and the L28 mobs (6 levels over my level) were really hard. The area with mobs L25-27 was SOOOOooooo much easier. Still had to mostly single target though, becuase 2x L27 mobs and I'd go oom. Nice to have 4x warsong sash's, decent blue for my warrior also. I'd recommend the author add this quest to his list of recommended.

23-34 SFK. Started at L23. Had to do a mix of single target and AOE pulls. Multiple wipes learning which mobs have AOE silence. Easy enough to pull correctly once you know how to pull it, just remember to drop off the kids a ways back before some pulls. I could not burn the final boss at L23, just kept wiping. Re-ran at L24, wiped once but got the boss down by just burning him and healing through it.

L24 - Tarren Mill battle of hillsbrad quests. Very easy to AOE them all. But it finishes with 2 quests to kill L30 mobs. Doable at 6 levels higher than me, but I went oom on all casters and needed mana pots to finish off. Recommend waiting till L25 for the L30 mob quests next time.

L25 - Ashenvale quests out by Zoram Strand & Thistlefur Village. Very easy to AOE them all. Stayed for a while to farm pages and herbs/ore.

L26-28 - BFD. Pretty straight forward, but wiped 2x - the murlock room chain pulled when I didn't pull them back far enough. Then on my 2nd run, I wiped again again just before the brazier room - damn humans running to get help. If anything, my problem was that it seemed "too easy" so I was overconfident doing mass pulls.

L28-29 - Back to Tarren Mill and Dun Garok quests. Ended up grinding almost a whole level in Azure Load in the mine in Tarren Mill. In hind sight I should have done something else. I feel like I could have optimized some quests runs in here, will change this up if I do it again.

L30-31 - RFK. Just did 1 run to finish warrior quest (mistakenly thought I needed that for Beserker stance - you don't, just kill the guys on the island). Very easy to AOE pull. But I did wipe one time because I forgot the bats do an AOE silence. Its easy enough to single target them from distance, but that's what I get for charging in and trying to AE everything.

L31+ On to SM....