Pros:
1. Lots of burst. You can easily one shot weak enemies after they skirmish with their lane partner.
2. Gap closer. If you spear an enemy, you have one of the largest gap closers in the game with your pounce. You can also use it to jump walls in the jg, making your path through much quicker.
3. Self heal. Having a jungler with a self heal makes life so much easier. Not to mention that it increases your attack speed, making it easier to kill creeps/take turrets.
4. More skills. Nidalee has 7 skills instead of the usual 4, making her one of the highest skillcap champs in the whole game. Use this to your advantage early game.
5. Traps. Your W skill in human form is bushwhack, leaving a trap that stays for 2 minutes. Leave these traps in bushes all over your jg, so you can easily find an enemy jungler trying to steal your jungle. These traps also mark them like your spear, meaning you do extra damage, and your pounce doubles its distance.


Cons:
1. Squishy. Nidalee is not a tank, she is an assassin mage. Remember this when trying to counter jungle, as tanks will not go down so easily.
2. Susceptible to CC. Crowd control will destroy you, as your only escape is pounce. A slow from an enemy can mean your end in team fights. Stay to the outside.
3. Lots of skills. While this is also a pro, it can be your downfall. Nidalee is very hard to use, and to use well. Keep track of what form you are in, and you win half of that battle. When learning Nidalee, I can't tell you how many times I wondered why my spear wasn't going off, when I was still in cougar form. Watch your cooldowns as well.
4. No innate crowd control. Nid herself does not have any crowd control. Unless you build the Crystal Scepter, you are straight damage. While this makes you less valuable in team fights, remember you can still stay to the outside and snipe the enemy, chunking down their health from afar.

There is really only one skill combination that you MUST memorize when using Nidalee:

Q R W E Q

Your first Q must be in human form. This is your spear. IF IT LANDS, immediately R into cougar form, W to pounce onto them, E to swipe and deal lots of damage, and Q again, making your basic attack do TONS of damage, as it scales on how much health the enemy has lost.

When attacking turrets, make sure you E yourself in human form for the extra attack speed.

When in a lane, always W the jungle around you so you can see enemies coming. If they hit your trap and you can kill them, it's R W E Q once again.

ALWAYS START GROMP. This is very important. If you are playing it safe in your own jg, stand in the bush by blue buff. When it spawns, hit it with your spear and immediately change to cougar form. Smite gromp immediately, and make sure you have a decent leash until it's almost dead. Then go directly to Blue, taking a point in your heal. Heal yourself and stand back, hitting it with spear at max range. Your spear will root it to the ground. Change to cougar and E Q it. Change back to human form and spear it again. Continue this, healing yourself as you go, until it is dead. Now you can abuse your heal as much as you want. Take a potion and move to wolves. They should be easy to kill but DO NOT WASTE SMITE ON THEM. Use smite for the raptor camp next, to give you true sight. After that, try to gank your mid lane. If your mid is gankable, do it. If not, go back and buy your Ranger's Trailblazer. Then it's smooth sailing. Get your golems for the heavy hands ability, then take red buff. After that, gank the closer lane.

ALWAYS WATCH YOUR BLUE TIMER! You are very reliant on your blue buff. Make sure to take it as soon as it spawns to prevent your opposing jungler from taking it.

YOU MUST BE ABLE TO LAND SKILLSHOTS TO PLAY NIDALEE! Period. No ifs ands or buts. Nidalee's spear is what makes her so good. Work on your shot, and you will be able to at least play her decently. But if you cannot land spears, Nidalee is the wrong champ for you.

Always aim to the left or right of a champion that you are trying to hit when they are NOT running from you. When they see your spear coming, they will naturally move perpendicular to your shot, giving you a better chance of hitting if you DONT aim directly at them.

If they are running TOWARD or AWAY from you, aim right at them. Most people don't zig zag away when running, giving you a better chance of sniping them as they run away. If coming towards you, they also aren't going to zig zag. If you hit them and they are low when chasing you, change into a cougar and immediately pounce onto them, performing your combo. This sudden attack will often catch them off guard and secure you an easy revenge kill.

This is what separates a good Nidalee player from a great one. Wall jump as much as possible to get used to what areas you can and cannot leap over. Then, if being chased, or chasing an enemy, it will be natural for you to shift to cougar form and W over those walls.

Remember, you can wall jump out of the back of the dragon pit, and out of the back of the baron pit. Those locations especially will help you lose enemies.

If you spear your jungle creep from through the wall, your jump will double. Use this technique as well to escape enemies through walls you normally couldn't get over.

There are maps online you can look up to see which walls are able to be dashed/jumped/spun through. Study these!