A leather shoelace, or something similar, attached to the end hole of the strap and tied around the headstock does the job. Straps are subject to personal taste, but I use the Long Hollow Softy for my F style. It would take some reworking to make it fit an A style, but there are straps sold as A or F straps. Folks have been known to install a strap button on the lower side of the neck heel as well. I did this to a Kentucky 250S I had, but I might not do it to an MT. If you buy a Collings strap, it should have directions for putting it on an A style mandolin.
"I thought I knew a lot about music. Then you start digging and the deeper you go, the more there is."~John Mellencamp
"Theory only seems like rocket science when you don't know it. Once you understand it, it's more like plumbing!"~John McGann
"IT'S T-R-E-M-O-L-O, dangit!!"~Me