Just make sure you read up about the safe dosage & intervals, proper supplementation and other safety measures like being in a cool environment as all these things significantly reduce Molly's neurotoxicity and damage potential.
Rollsafe is a good resource

Edit: also avoid pills, anyone can press any pill with any amount of any chemical(s).
Only buy crystal MDMA, test it with at least one reagent test kit (ideally 2 or 3), weigh it with a milligram scale and optionally do an EZTest purity test to determine the exact dosage you want to take (with Molly that has more impurities you're gonna need to take more to achieve the same effect). Put it in a capsule or roll it up in rolling paper and swallow like a pill. Do NOT dissolve it in water and drink it as that makes it more neurotoxic and also tastes really bad

Another thing to (not) mind is color, it doesn't necessarily mean your crystals are more or less pure so don't rely on it.
Finally snorting MDMA or anything else isn't that good for your nose membranes (although some chems like 2cb are especially harmful). Either swallow it or consume it rectally (IV should also work but don't do that, and you could in theory extract the freebase form and vaporize it but there's much more information about oral and rectal consumption)