Yes, the phrase "SUGGESTIONS TO FUTURE PARTICIPANTS" is grammatically correct. It means that the content that follows will provide advice, recommendations, or tips directed at individuals who will participate in an event or activity in the future.
Here are a few ways to rephrase it:
1. Recommendations for Upcoming Participants
2. Advice for Future Participants
3. Tips for Those Participating in the Future
4. Guidance for Future Participants
5.