If we talk about Bitcoin, no specific criteria. Just buy and accumulate as much as possible "only if" you understand what you are doing.

If we talk about altcoins, depends on market behavior and trends. Riding a hype is risky but if we play it right or should I say "timed it right", we can actually take advantage of it. Of course, strategies vary per altcoin as there are lots of them.

Having specific criteria is hard to set in the volatile world of crypto. Experience will teach us the possible right next move we can consider.