I highly recommend actually staying in the 20-60 range zones until you ding 62. The reason for this is that despite getting a slight penalty in experience for being over-level, the advantage of having flight will more than offset this. That, and WOTLK and TBC zones are the slowest part of the leveling process. Minimizing your time there as much as possible is worthwhile.
Special mention is the Darkmoon Faire Top Hat and WHEE! buff. While not always available due to the DMF being inaccessible most of the month, if you happen to be leveling when the DMF is running, it might be worth your time to go and get these. AFAIK they do stack with heirlooms, although I have not personally tested it. Fair warning: These buffs do NOT stack with each other, and the hats disappear after the DMF goes away later in the month(unless you only log in when the faire is running).
the guides work great for leveling almost in autopilot, also the zygor guides work great, the only problem is that this 2 companies moved to a monthtly fee payment model for BFA, not worth the money that you are paying if you ended up paying almost the same as the game monthtly subscription. Recently there is a new free addon for leveling in curse addons webpage that do this without the payment, is not as advanced like the pay ones but works. i will leave the link below. We need to support this kind of free addons.
NOTE: It is VERY important to not vendor any equipment you pick up. You will be deconstructing all of your gear for resources that will help you in the Warfronts to be fought! Deconstructing, or scrapping, your gear will be done using the Scrap-o-Matic 1000 if you are Alliance and the Shred-Master Mk1 if you are Horde. This works the same as the way the Obliterum Forge worked in Legion. The scrapping feature can be used on all Battle for Azeroth equipment found, not just craftable equipment, so save everything you acquire for the scrapper! Before we get started, keep in mind some of the tips below that can speed up your leveling process!
/way commands like /way Shadowmoon Valley:Draenor 50.0 31.2 Ashlei don't work correctly. According to the way TomTom works, this waypoint should be created in Draenor's Shadowmoon Valley. Instead, it will be created in Outland's Shadowmoon Valley. So it seems there is currently no way to distinguish between zones that occur more than once with the same name, such as Shadowmoon Valley or Nagrand.
I do not recommend going for TBC, although I remember Hellfire peninsula to be decent, everything else is rather slow. Instead go for WotLK, Borean Thundra gets you levelled very fast, and then you can head straight for Icecrown at 67, which is also insanely fast, although admittedly has a few elite quests. You can go to Sholazar Basin alternatively. 2 zones should get you 60-80 no problem.