For you to know that is a promising project I know you have done your assignment well on the coin. For me If I have the fund and like you say if the coin is promising I might invest with some amount which may just be small amount so that whatsoever happens I don't regret.
The hard question is how to know whether a project will be promising or not. Its a hard work thing to do tho. Cuz we have to research for a bunch of stuffs before deciding that a project is good to follow or not. Luck is also play some role in this type of investment. But yep, its better to risk only small parts of our capital that way, if things run against us, we wont lose a lot.