Hey there, my name is ChAoS379, and this is my first guide to Niding, that is, play as Nidalee.

For runes I take magic pen marks, flat armor seals, flat magic res glyphs, and flat ap Quints
Marks are standard, and it gives you some good harass against champions whenever you land your spear, and no more magic pen is needed since your w takes down a percentage of their resistances as well. Flat armor and flat magic res are flat since early game you don't want to be losing health, and if you get harassed it greatly helps, plus in cougar form you get 10/20/30 extra armor and magic res, so without any other tanky items you'll have around 120 armor and mr. The problem will be you won't have much health, but her heal will give you a good 20% or so of your hp back whenever you use it, if you rush deathcap first. the flat ap quints are there instead of hp or mv speed since the spear, the trap, the heal, the pounce and the swipe all benefit from it, if you're careful and play well you can be backing the first time around lvl 8 and with a hefty amount of gold. Also, starting with the mana ring gives you a total of 31 ap counting Quints at lvl 1, which makes your traps very strong damage dealers aside from the usual use for them.

I go with the standard 9/0/21 since I enjoy the extra cd and mobility bonuses at the end of the Utility tree. however, I put 1 point in Good hands and 3 in perseverence since nidalee shouldn't be dying, although imo the bonuses given by 4% increase aren't that much when you have only 8 health regen per 5.
In the offensive tree, take the ap, the cooldown and the magic pen, since these will help you deal more damage, and take the mana regen, the increased xp and the buff bonus time for utility as well as cooldown for summoner spells and cooldown for flash. The xp will help you get to lvl 6, which is when you can stay in cougar form for a while while the mana regen kicks in, and plus the tanky bonuses it provides plus the move speed and pounce make it definitely worth it to get to lvl 6 faster than the opponent.

For starters get W. Always. w is not only a must before level 6, but it also has the most damage from all the skills (except for spear at full range) at lvl 1, gives you visibility and considering the cooldown and mana regen you have, you can cast it every time and regen all the mana by the time you can cast it again. It also helps as a leash for the jungler as well as protection for him and for you from ganks, since it acts as a free ward if they walk through it, so spamming that at lvl 1 is a good idea. The skills you choose afterwards become rather situational, if you are laning 2v2, a heal is a good idea, and after casting w a couple of times you've warded enough and can concentrate your mana pool on healing your partner and yourself when exchanges happen. If you're 1v1, you get heal if the opponent is being extra careful or if he is harassing you and you don't like that. Spear at lvl 2 is usually only when the opponent doesn't know what it means to lane against Nidalee and likes to stay on the sides. It is also good if you want to scare your opponents if they're staying too far back and you poke for 20% of their health with the spear specially when they're standing next to each other.
In the rare case you're solo top, and your opponent doesn't have a jungler, going for two levels of e (at lvl 2 and 3) is actually a good idea, if the enemies are good. Otherwise, get the spear.
By level 3, you should have one level of each, and use the spear only if you can hit. after level 3 you either start maxing the spear or if you're getting harassed take one more level of heal to make sure you survive.
Nidalee's spear is one of the best skills shots imo. It has an incredibly long range, and it can deal up to 250% of damage depending on how far away it is from you when it lands. It can reach up to that champion trying to b behind the tower without you getting hit, and give you some of the most hilarious kills when the enemy runs into it without meaning to.

So, at level 6, the priorities should be R->Q->E->W when leveling up skills, also remember to use traps in narrow passages, as well as in bushes so you can tell when a gank is going to happen or just where the enemy is at all times. Map awareness is facilitated with the map control provided by Nidalee's traps as well as warding. Use w to ward dragon and baron as well and your team will have the upper hand if the enemy tries to take them.
Overall, playing as Nidalee means that you gotta learn how to land a skill shot that takes one heck of a scary amount of health from your opponent. Warding the map for a small amount of mana, and healing that champion that would die without your help. It also means turning into an awesome cougar that can jump around and kill enemies and is only restricted by cooldown to be able to spam more.

Starting out get Doran's ring. Not only does it give you a good amount of ap and some mana regen, but also some much needed health. This item provides everything (and then some) that Nidalee needs at lvl 1 to be laning for at least 10 minutes, plus you get to spam traps as much as you want.
When you go back for the first time you should have around 2k gold at least, so buy a needlessly large rod, and a pair of boots, if you can, buy a ward, and if you went back with more, ie 2.4k gold instead, buy the boots, nlr and some magic res.
Next time you back, finish your deathcap and boots, this should give you a great amount of mobility and ap to last until you can buy another full big item. Then just follow the item order provided on top, guinsoo's first if you are doing well and you can remember to spam your abilities in cougar form, lichbane if they are building armor and you go back with around 1300 get sheen first and build into lichbane, which helps push like no other.