Welcome Marcus, good to have you around
Honestly? Lab tests first, then reviews, trust score last.
Lab tests cause that's the hardest thing to fake. But its less about "do they have COAs" and more the details - how recent, is there an actual batch or lot number on it, and who did the testing. A COA from a year and a half ago on a shop thats shipped a hundred batches since is basically telling you about a vial your never gonna see. And a lab with a public verification portal where you can punch in the report number yourself and pull the original, thats worth way more than one you just have to take their word on.
Reviews second and honestly read the bad ones first. How a shop deals with a batch that went wrong tells you more than fifty people going "fast shipping A+". Also worth checking if theres actually a decent number of them or just like two.
Trust score last, and take it with a grain of salt on shops that dont have much data yet. If a shop's got two reviews and one test the score isnt really saying anything, theres just not enough there for it to mean much. Gets more useful once theres some volume behind it
Oh and one thing people totally miss - check if the COA covers quantity/content not just purity. A vial can come back 99% pure and still be underfilled. Purity number alone wont catch that
check their social medias.
anyway thats my order, curious if anyone does it different