Poke poke poke. The reason that you prioritize mana regen early is to increase poke. Your Q does a surprising amount of damage even with a low amount of AP, the challenge is hitting it, more tries.. more success.
Once the enemy champs are low enough, if you hit another Q you can switch to Tiger form and leap to them and blow them up.

Nidalee has a very nice Q in either form. In human form it is quite a good poke weapon while in Tiger form it is a powerful bite that deals more damage the lower the enemy is and has increased damage if a Javelin was hit prior to the bite.
Therefore for the nuke combo you will want to hit a Javelin and then press R to switch form, press W to jump onto the enemy, press E to deal some extra damage and then press Q to finish them off.
Late game this can easily deal 2000 Dmg or essentially one shot an ADC, the bite alone can deal over 1k with the same applying to the Javelin.
Add dark harvest to this and you can oneshot bruisers too.

2 things.
You are not a front liner, you have a heal.

If you are having a small skirmish and you hit your Q, always go in if they are a squishy as you can most likely either kill them or get them low enough for your team mates to do so.
If your team mate gets caught you can heal them.. do so. This might also give you enough time to do the Nuke

You are not a from liner.
You stay behind your team spamming Q's until you hit one of their squishy targets. If they are close enough you jump on them, if they are not you can either flash jump followed by a Nuke or you can zone them off.
You can make it out alive after the nuke in most cases as your W is usually up in time after the kill and your team has way more pressure so your front line is closer. The way to do this is W while still in tiger form them immediately press R and then E on yourself to heal.