What actually helped you improve meeting room acoustics without hiring a contractor?

I'm looking for ways to improve the acoustics in a meeting room without bringing in a contractor. I've been reading about things like acoustic panels, room measurement apps, sound absorption solutions, and other DIY approaches, but it's hard to tell what really makes a difference. For those of you who have worked on meeting rooms, conference spaces, or office environments, what helped the most? Was there anything that noticeably reduced echo or improved speech clarity?