Its not possible to earn 0.3 even in a month only from signature campaign, as payouts are limited and you cannot exceed that amount, but trading can contribute in earning that amount.
BTC0.3 is possible even you are not in signature campaign. It's far more realistic than
BTC0.3 in a week.
There are lots of people now who can do that earnings for a month by maximizing their all known methods to earn bitcoin. It needs work and efforts though to make that possible.
It is really possible to earn .3 btc in a week. Some are suggesting trading bitcoin and I agree to that - only if you know and have the right skill to trade btc online. But for those newbies, trading is risky like gambling because newbies doesn't know well yet the fundamental and technical aspect to trading.
If you are still a newbie, I would suggest spending some time getting free faucets online. There are many of them out there. Mostly pay on a weekly basis. Once you accumulate some btc, you can then try your luck in online bitcoin dice games. Create your own strategy and stick to it - don't let emotions dictates your betting.
I get .2 btc in an hour from .002 btc in from playing dice online. but of course, this is not always the case. You win some you lose some.