With all of the recent shit that has went down and has effectively decimated the dnm community, I feel like this community is in need of some advice to help them prevent making mistakes which keep enabling feds and thieves to run off with their coins.
When selecting a marketplace, the first most important factor is longevity. If a market has been around for years, it shows that the staff is somewhat competent. This shows that the staff not only has enough technical knowledge to have prevented destruction at the hands of random hackers for long periods of time, but that the staff is also dedicated to running the marketplace and will not simply disappear after a few months of operation.
The second most important factor is the popularity of the marketplace. If a marketplace has been popular for several years, it shows that it is able to hold up to heavy scrutiny, and also makes it very unlikely that they'll decide to run off with your coins in the small window available to them. There is nothing you can do if a market that has been running for years suddenly decides to fuck everyone and disappear, but if the market has been popular for a long period of time it's very unlikely that the market will close in the few weeks that you are relying on it. If you are a vendor that always has a decent amount of coin in escrow, and do not use something like proper multisig, you must realize that eventually the market will fuck you, prepare accordingly.
The third most important factor is the security of the marketplace. It is inevitable that some flaws WILL be found. With this in mind, try to find any publicly disclosed vulnerabilities. Not all vulnerabilities are created equal. If it's a simple overlook like alphabay's api message enumeration vulnerability, it's not a big deal. If the vulnerability is something involving not sanitizing inputs correctly enabling sqli or rce, that is a big fucking deal and you should carefully consider using the marketplace as that can indicate some serious architectural problems. If a marketplace ever has coins stolen from it, in any way that is the fault of the marketplace, DO NOT USE IT HOLY SHIT. I honestly cant believe that people were stupid enough to use traderoute after that was disclosed.
There is much more to consider before choosing a marketplace than these three factors I've listed here, but if you consider every marketplace through the eyes of these three concepts, you will minimize your chances of getting fucked. Do not trust new markets to hold your coins, unless you are willing to lose them. Do not trust unused and unpopular markets to hold your coins, unless you are willing to lose them. Do not trust markets that are ran by incompetent staff with no understanding of security to hold your coins, unless you are willing to lose them.
And finally, another important thing to remember that involves points #1 and #2, DO NOT FALL FOR THE SHILLING OF NEW MARKETPLACES ON THIS FORUM. Do not trust ANY market recommendations that are for anything but the current behemoths. Alphabay, or in today's time dream, has no reason to shill. Therefore you will not find people pushing the most viable markets to use in posts and comments, they will always attempt to push their own underdog marketplaces.
I have not covered every single thing you should consider before choosing a marketplace, I don't want to write some fucking 200 page essay, but if you follow this advice you will minimize your risk of being fucked over by market admins.
Tl;dr: If you want to minimize your odds of getting fucked over, consider the following: #1 Longevity, #2 Popularity, #3 Security
Didn't even bother to read, if you can't safely buy drugs at this point you shouldn't be on the darknet. ALL THE INFO YOU NEED is literally listed at the top of page in the dnm Noob section. If people can't read and figure out shit they deserve to be arrested imo.