Nami is a hard to understand champion. Shes fun to play though, I just don't like her damage output. She has mechanics that may work pretty well with an ADC, so... I wanted to give it a shot. Her E acts as a slow and will keep the targets in range, her W is a heal, and her Q is a root. Lets not forget her AMAZING CC ultimate.
This ability acts like an extra pair of boots. With this passive you should ALWAYS hit yourself with your W or E first, especially considering you have a Muramana to help you out.
This ability is very useful for stopping enemies dead in their tracks. The wont be able to get to you for a couple seconds so use this time to your advantage. If you can E yourself and auto attack them a couple times.
This is actually a pretty strong heal at base "damage" max level. It will also deal a small chunk of damage to the enemy. I wouldn't rely on it to keep you alive though. Thats were your auto attacks come in.
With any luck this ability will be your main source of damage. and the ability your going to want to max first. It offers 3 basic attacks with extra damage which is a really nice addition to an ADC, also it gives you a movement speed boost in team fights.
Using your ult or even remembering you have it is kind of a pain. Sometimes you don't know when to use it, or maybe its your teams only big initiator and it saves you the game. You'll never know without casting it. Just give it a whirl and hope for the best.