The easiest way to get a bitcoin is to buy it. Other than than that, there is no easy way to have a bitcoin. You apply signature campaign but it will take a long time to make your earnings to be a whole bitcoin. You have a lot of work to do before you can have a bitcoin.
OP says, except buying bitcoin, what are the other ways to earn it... I think, since OP is already a signature campaign would make him earn...While doing signature campaign he could try data entry jobs too, by that I think that won't take him more than 4 months to have his first one whole bitcoin...
bad without reading what was said by the OP. and buy bitcoin can not be said to be getting bitcoin productively. it's just convert your money into bitcoin , and you do not get any benefit from it. yeah, there's no free way better than just a signature campaign. but when you've got the results of signature campaign, you can grow it by trying to trade, I think it could be fast enough to get bitcoin.