The only calls I can reliably get my teammates to do is dragon, and even then only as support or jungler if someone else isn't already thinking it. call the timers: "drag 1:45, preparing it" while recalling is typically enough to let them know that their thresh is going to be fighting the vision war near the dragon pit in about 30 seconds, and therefore will not be near enough to a toplane or top jungle to help. following through with one pink, an upgraded sweeper use, and dropping 3 sightstone wards on likely incoming enemy paths is like a gigantic neon sigh saying, "Take this, we have vision and they either can't fight us or can't find us" without you having to communicate any of that. To be fair, I can only speak to silver and bronze experiences, where they won't realize you're doing this until it's far too late to trade anything back for it, and you also can't get your team to turn off dragon and fight them if they just run in and contest, but it's a start.
Basically, make the call ahead of time, then stay focused. Don't call dragon timer at one minute, then take top inner turret as a jungler, or scream for group then immediately farm wolves. Of those that listen, even the worst players actually do realize that a bad plan followed well is better than no plan followed perfectly, so follow your own plan and you might find other behind you.