With my original druid, I leveled up to 60 as a feral spec and changed to Restoration for dungeons and off-night raids. With the release of The Burning Crusade, I made her my main rather than my warlock, switched her to Balance and began the upward grind with the original intention of going back to Restoration at 80 for raiding. I never planned to fall in love with the big ball of feathers on my screen.
This time around, my desire was to actually level fully as Balance. This has provided some new and more interesting challenges since the actual Moonkin form is not obtained until level 40.
o Just because you aren't heavily armored doesn't mean you can not take a hit.
A lot of the moonkin guides I'm seeing say "Root, root, root!" Is it really necessary? Sure, you're not taking hits so you're not having to heal yourself, but with the mob's chance to break the Entangling Roots early and any damage done having a pretty good chance of breaking it (even when talented), it does not actually seem as useful for one-on-one fights.
My alternative is what Graylo calls the "machine gun method" in his blog. Even under-geared and even or lower-level compared to the mob you're after, if you make careful pulls you should find no problem.
My typical rotation can hardly be called a rotation: Starfire, WrathxN. If the mob is yellow and not a caster or other low-hp creature, it becomes Starfire, Moonfire, WrathxN and while waiting for the Global Cooldown after Moonfire, back away; those few steps could prevent one more hit over time which is slightly less damage taken.
I generally can get four mobs to a mana bar, unless they are lowest-level green and then occasionally I can squeeze in a fifth. Before you mana up, throw Rejuvenation on yourself or, if you're completely Out Of Mana, bandage yourself. Which brings...
o Don't overlook First Aid.
Sure, you can heal yourself. That's great! ... until you run out of mana. If I find things getting too rough but the mob is almost down, I'll Entangling Root it, back up and bandage, and wait for my mana to regen for one last Starfire or Wrath to take him down.
o Use a dagger (preferably a fast one) rather than a staff.
Lag is, well, lag. There's not much that can be done with it. IceHUD colors my casting bar, letting me know when I can likely start queueing my next spell due to latency, but it's not 100% accurate. By having a fast dagger as a weapon, there's a greater chance that during that lag time of ending the last cast and starting the next one, you'll be able to get a hit in. Every little bit helps, and it could be the difference between the fleeing mob having 1 hp left after your last Wrath or being dead. It also help with runners with very little health left as you can usually stab them down rather than waste the mana for another Wrath.
It remains to be seen if it is still the case, but for a long while a one-handed weapon and and off-hand implement had better overall stats than a two-handed weapon.
o Don't waste your talents on DoTs.
People put a lot of emphasis on Druid '*-over-time' abilities. But Druids are not Warlocks and our DoTs will not generally have an opportunity to fully run their course. I always check to see how long it takes to kill a mob with Moonfire and without it in my 'rotation'; creatures with lots of hitpoints or nature resistance/immunity will certainly die faster with Moonfire in the mix. In general, however, that is usually not the case and the extra damage that did not trigger equals mana wasted.
o Don't spend your coin on Feral skills.
The only ones I'd suggest picking up are Cat Form and Prowl for those times when you really don't want to have to kill everything in your path. Without proper gear and talents, your feral damage is not going to be anything spectacular. You'll be better off saving that coin for more useful things (like training your Balance and Restoration skills, profession materials, Auction House fees, and your mount/riding skill.)