Probably just go online and be on the Internet... possibly post something somewhere. I might listen to music. It wouldn't surprise me if I posted here prior to any attempt. It also depends on the context...
If I think someone is coming to do a welfare check on me and I might be involuntarily hospitalized, I may not have time to do anything other than attempt. So it could be just down a bunch of meto as fast as possible, dump SN into water and don't even measure properly, start throwing up but hope I absorb enough SN to die, and wait and hope I die before someone forces me to engage in involuntary inhumane treatment again.
It's unlikely that would happen, probably. I had one welfare check before where I could see them coming and ran, but it's unlikely I'd get advanced warning or that they would break down a door... The last welfare check they knocked, I didn't answer, then they sneakily waited for me for many hours (I eventually went to the peephole and looked, hours later and they were waiting like the vipers they are), so I just stayed silent, tip-toed back to bed at 3 PM, and didn't move for about 15 hours, then they left. I also left that place in part as a result of that, I dislike and fear mental health professionals and couldn't feel comfortable after emergency personnel had stopped by... I kept feeling like they could come back... I just want mental health people to leave me alone forever, please let me never see another mental health professional ever again.
It's also possible it wouldn't be rushed, and in that case, I think I would probably take xanax if I had it, probably post on here, I might write some emails with a delay on them... I think I would like it if I could do a proper SaSU goodbye thread... but I would probably be doing that only if my suicide were extremely organized, like everything boxed up or sold, everything just right. I probably won't end up doing a goodbye post... Just a guess...