With signatures the maximum you will earn monthly will be around 0,15 btc with high paying signature, soo isnt a low ammount but is hard to be and remain there as well find a free spot, trading is the easy and better way to make such income monthly, eth, doge, and almost all top traded coins at poloniex had raised a lot last months, and all days some coin is being pumped, if you lucky you will had invest into it.