If you don't have money to invest in then you can try our forum to make some bitcoin by offering service and also joining signature campaign which is only needed is time and small effort in posting but it is all worth it because you can earn enough profits but don't forget that you need to be patient in order to be successful on this risk free way of earning bitcoin.
yes that is a good choice but i think it also need ability and skill, for example if you are a good designer then you can get good profit from this skill. signature campaign income also depend on your rank if your rank is good then you can get good number of bitcoin from signature campaign.
I think signature campaign is the best and safest way to get bitcoins irrespective of the rank that you are holding as it will surely give you certain amount of bitcoin over a period of time and it spending time on forum will also increase your knowledge related to bitcoins and you will find many other ways of earning bitcoins and that will really help you in long term.