What I mean by decent is where you can really see that it is growing and it can give you profit that is enough to be reinvested.
Call me dumb but I really don't know. I'm sorry.
My only source of coins is my signature campaign. I earn about less than 0.1 BTC per month.
Any advice would be much appreciated.
i believe that there is no one right answer to this question of yours. because the answer solely depends on how much money you own. for a rich person investing a million dollar is a "decent" investment and for a poor guy investing $50 is still investment and the rest in between. so you have to come up with the number yourself.
and obviously the more you invest the more you can earn and also the more you are risking.