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 could say $1,000 because any amount less than this can be used for trading of course but the risk is lower so the profit it is, anything higher than $1k can be considered ad a decent investment and maybe sometimes it isn't enough.