Until level 40, if you're specced feral, you can tank pretty well as long as you've gotten a few bear talents on the way. At 40, you should seriously consider dual-speccing if you plan to run instances. The queue time for tanks is very low; for healers, as well.More WOW Gold,more Cheap other gold in mmolive.com!
Pick up either a healing spec or a tank spec if you're going to be doing instances a lot as part of your level strategy. Otherwise you can stick to strictly feral dps if you don't mind the queue times.
You'll need stamina as a tank, and AP as a dps in kitty form. Definitely avoid intellect and spirit as a feral druid. If you do plan to heal or cast, then you will need intellect and spirit gear, but otherwise you don't.
You might want to build offsets for future builds you spec into. For example, if you think you might be healing later on, collect intellect and spirit gear that you can store in the bank.
Be sure to pick up the mangle and rake glyphs as part of your feral spec. At level 75, get the berserk glyph as well to fill out your prime glyphs. Rip is another good one to have for a feral spec.
To recap, you should spec feral for leveling druid, consider a dual spec when you're going to be instancing a lot as you level, and make sure to weigh your stats. Look for stamina, strength, and AP gear for feral; intellect and spirit should only be priorities for casters.