Hello, this is my first Guide on Mobafire, I hope i have used this one for Nidalee since the last Heal nerf and it works fine for me, I hope it does also for you :)

For Runes I use :
Magic Penetration Marks
Mana Regen / 5 / level Seals
Flat AP Glyphs
Flat AP Quintessences

You can Also use armor seals and magic resist Glyphs, but i prefer the others, use what works best for you ;)

For items, i get sapphire crystal first, because since the new patch, nidalee is very mana greedy, you can also start with a dorans ring for the Ap and HP, but u will be able of healing / harrassing much less.
then once i farmed enough gold for catalyst and boots i recall and ask the jungler to Defende My lane.
For boots, you have a big choice. you can get the Cooldown boots, Magic pene boots , Magic resist , or dodge boots, it's all situational and depends on your gameplay. I always use Magic pene or Magic resist :)
If your team does not give you Blue buff for whatever reason, i also like getting chalice of harmony , but when your team gives you blue buff, its just a waste of gold
after my rod of ages i rush rabadons. this is my core build
then it gets pretty random / situational, there are a lot of people who like Lich bane on nidalee, i don't really use it every time, but i put it into my item build since so many people like it.
Then you want to get Void Staff if they have a lot of Magic resist, but you can also go a lot tankier and get a rylais, wich is pretty nice since nidalee has 0 natural CC.

i put the guardian angel because i can't put all the tank items in the box.
You can pretty much get every tank item you want, like sunfire / Banshees/ etc
But GA (guardian angel) is my favourite since it can save your life and gives you Armor and MR.

Flash - Great escape skil / hunting skill, you can easily take somone down with Cougar form when he lucks away with flash + W + Q

Ghost - Very nice to get away or hunt, makes you so fast and when you walk in bushes no one can follow you

Exhaust - :)

Ignite - *neutral face* i don't really like this on Nidalee, Dunno why

Cleanse - :D

Clearvoyance - Leave this to your supporters :/

Clearity - nah, you got blue buff for this

in ranked, you always take Mid (or solo top if necessary, but nidalee isnt as strong as she used to be after the HUGE heal nerf)
you just farm creeps and try to harrass your enemy, espacially at lvl 6, since you can easily take somone down at half health without Magic resist, but you dont want to over extend since your heal now costs huge amounts of mana and it heals only about 70 - 300.
Dont forget to put traps in the bushes so you can see if somone wants to gank you or not.
Ask your jungler to give you blue buff since you will NEED it. but only do this at lvl 6 + because your jungler will need it more in those early levels than you do.

Pros -

- Epic Lategame
- Epic Midgame
- Can be hard to follow / escape from
- Deals Tons of damage with spear
- Lovely Animations
- Is Female :)
- My favourite champ :D

Cons -

- Hard to master (like almost every build says ._.)
- Even Harder to play after Heal nerf
- Weaker early game
- Very managreedy
- pretty squishy
- Very hard to play in Low ELO games