Your wallet has to be online and either unlocked or non-encrypted. That's all.
The process is random, the more coins you have and the older your coins are, the more chances you have to stake.
So how will we know the age of each coins we have? And If a coin is 51 days old or more is it still going to stake or not? Well, you can look at coins in your wallet by using 'coin-control' 'Settings, Options, Display' check 'coin-control'...
They will show the inputs as 'highest', 'high', 'medium-high', 'medium' etc...
And yes, your wallet must be unlocked and not encrypted to stake... and you must not set a reserve balance in either your captcoin.conf file or by hand in the debug console...
Coins older than 51 days will be highest priority to stake...
We have a lot of CAPTcoin wallets out there, thousands... my guess is staking is just a lot harder than it used to be...