How can I generate more coins while mining on PoS? I couldn't find the specifics on how would one get more coins with PoS.

I understand that with PoW one gets more coins by having more hashing power and running software like cgminer.

With PoS, I need to have more coins, and… what else? Just have the client open? If that's the case, it's kind of risky, isn't it? I mean I would have to have my private keys in an online machine?
Yes, you have to have client with all your coins open with your private keys and have it sitting on online machine.

See Proof Of Stake Details section for NXT