Hi Winter,
Levelling a druid is real fun if you have patience upto level 50's. After getting mangle ability, it goes very smoothly. I have used as reference, Mihir's Druid Levelling guide. It is very simple but effective. You can find this guide at druid wiki. Feral levelling is the easiest way to level but you may try to level as resto (not adviced but if you like it who can say anything
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Other than slow levelling at early levels, there is one thing I need to say about druids: You will need lots of bag space. Because, you need to carry DPS set, Tank Set, and healing set with you.
You may not know when you will need to be tank or healer, unless you have strict planning to follow one path as dps, tank or healer. But remember one thing: Druid means flexible playing. You have to adapt yourself according to situation.
Good Luck and have fun
