Newbie zones, same as always.
The Warrens is a nice earlier teens area, as is Kurn's Tower. Mid to late teens are a great time to try and get into a group in Paludal Caverns, or try soloing in Everfrost. I preferred pulling from -1500, -4000, doing all the roamers around save for the orc shamans, who will root you and nuke you and al kinds of nasty stuff. Melee + nuking works to a degree, as does traditional dot kiting and root rotting. But the dots are fairly crappy at this point, so grouping is recommended.
Everfrost! Lots of Everfrost! The mammoths should be your targets, root rotting solo or fearkiting with a melee partner or small group. Their tusks sell for 10pp each and there is a merchant nearby who will take them off your hands (they're literally worth their weight in plat). If you're more daring than I you may even want to try charming them. Just remember to snare the pet and the mob it's fighting for when charm breaks. HHK is good in a group too.
I liked root rotting in The Overthere, but there's also charm kiting cougars near ToFS in Iceclad, and grouping in HHK.
This is it, the best time to be a druid! I start by doing as many levels root rotting HGs for money as I can stand, but if you're just leveling an alt then the real xp is in Eastern Wastes at the ulthorks. You'll want to quad these. Their HP is fairly low, but I advise having about 200 wis to manage these without KEI. I'll explain quadding later in the guide.
Spectres in Oasis of Marr, another great quadding spot. The pull can be a bit tricky, but is manageable. If you do pull more than 4 (there are 8 spawns with large aggro radiuses), just ensnare them all and nuke until 4 are dead, then zone out and come back in to clear aggro. They drop scythes which sell for 13pp, bronze scythes which sell for 3pp, and rusty scythes which sell for crap. They are pretty solid cash though, and amazing experience. I made 7 levels in 4 days here.
Wyverns in Cobalt Scar are good, but you need a very large mana pool (255 unbuffed with some solid +mana items) to handle quadding them without KEI. DSP hoppers are also good at the high end of these levels, but have around 500 more hp than Wyverns. Do not try hoppers before 49 when we get Lightning Blast.
Group! Seriously, at this point solo experience seriously declines and it becomes much faster to level up in a group than any druid soloing techniques.
However, if you really want to solo, charm kiting is your best bet. Once you hit 52 and get a nice little xp buffer, pick up Call of Karana (animal only charm) and head out to the Plane of Nightmare. Note that it is better to wait until 53 when we get Glamour of Tunare (animal only magic debuff). GoT makes charms last significantly longer in my experience, much longer than the statistical -20 MR should (leading me to believe it covertly decreases the chance of the animal breaking charm). You're going to the Ravenous Stalkers (ask me in game and I'll show you the spot). You can stay here right up until 63 when we get our next charm if you like, although xp will slow around 59 or 60.
You've done it, reached the maximum level! Ready to start grinding out hundreds of AAs!? I sure hope so! As with everything post 50, grouping is typically your best bet, but 65 opens up another option you've probably forgotten about by now: quadding! Once you hit this high level and get some decent gear (4-5k mana without any AAs is solid), you can start thinking about visiting my friends in the Halls of Honor.
Our targets are the humans (A Valorian Guardian and A Valorian Guard) in the basements. I personally camp the NE basement, the room just outside Trydan Faye's room, but any of the three basements work (NE, NW, SE). As with earlier quadding camps, you'll want to grab four humans with ensnare, run circles around them until they're one solid pack, then unleash your druidic wrath (Karana's Rage). They have around 25k hp (9k mana worth of nukes), but are doable with 10+ FT, KEI, and some basic mana pool and mana regen AAs, but you'll want at least 5-6k mana to really handle the camp easily.
You'll want to have Ensnare, Call of Karana, Savage Spirit, Glamour of Tunare, your current root, your current single target damage shield, your current largest heal, and some method of killing the mob yourself (I prefer to use our current largest DoT, or just clicky epic DoT). Innate Camo or a clicky invis is incredibly helpful.
There are two approaches, one which pits two unbuffed mobs against each other (one being your pet) until they're both very low on hp, then breaking invis and killing both yourself for full xp. The other approach involves making one a more permanent pet, buffing it up after charming (with SS and DS), and pitting it against 2-3 mobs, letting it kill them (or breaking charm, killing the mob and re-charming the pet), then eventually killing off the pet when it get low enough on health to no longer be worth keeping alive. Once we have our CH, it becomes more reasonable to keep the pet alive as a permanent pet than to ever break charm and kill it off (avoiding having to rebuff a new mob and waste time going through the whole process of grabbing a mob and making it a pet).
Charisma is the most important thing when Charm Kiting, without high cha your charms will be resisted and break very frequently. A pair of Opal Encrusted Steins and a Bracelet of Beauty will raise your cha by 65, which gives a pretty good charisma for wood elves and humans, but will leave halflings at just over 100, so halflings in particular need to invest in a set of cha gear if they plan on doing much charming. When charming, charisma is more important than wisdom and FT, and should be treated as such.