For some years I have used a version of a strap or flipper or duck’s foot on my horn. While the other straps I have used have had a button that soldered onto the horn to hold it in place, there is a version that just straps on the horn with Velcro. I finally purchased one of this type this spring, and it is in this photo. It is a Fhrap (TM) made by Leather Specialties Company. The maker describes it as follows:
The Fhrap wraps around the horn where the left hand grips. It relives tension in the left hand in order to relax the musician. Good for beginners!
I find it works pretty well, especially with a lighter horn such as this one, the single B-flat in the previous post, but I prefer the type mounted with a button. This version is an option certainly worth a try if you have any hand problems, it does make holding the horn more ergonomic.
UPDATE: See also this article on how to position the strap when holding the horn.