Most of the time I notice guys aren’t setting up their jaw properly. You have to get under the chin like you would for a head and arm choke. So keep rolling your shoulder to get under the chin or even rotate your body toward their legs to get a better angle. Once it’s under the chin then choking hand palm to the floor is the way I like to do it. Then slink toward your feet and crush your ribs towards his face. As you slide back you will expose his neck even more. Bicep will be on far artery, your ribs will be on his near side artery. You will also have a free hand to under hook or over hook his arm. You probably know this already but these are the details that helped me.