I'd imagine it varies greatly, depending on the type of entity being secured and contained, but what sort of off-the-shelf techniques would MTFs and Agents use to initially secure an anomaly prior to it becoming a contained SCP? Some things just are discovered and moved into containment, but if we're talking about some animal-ish thing, how might personnel go about catching it? I understand tranquilizer darts require some knowledge of a creature's physiology (weight, anatomy, etc) to actually be useful, and electric stunners have limits. And, for that matter, there's no guarantee either would work on something, considering how weird some of the stuff that needs to be captured is. Obviously, the Foundation wouldn't want to kill something if it doesn't need to. To reach into mythology for the sake of argument, how might the Foundation contain a ghost (as traditionally described)? Or a dragon? (And no, I'm not suggesting either of those as potential SCPs, simply as examples.)
I suppose the short version of this is: What sort of techniques and equipment would make up the "toolkit" for initial use prior to necessarily knowing anything definite about a dangerous entity? This might be an interesting thing to write up as an "in universe" orientation (beyond the Red Dawn one Waxx drafted a while back).