I am not getting any replies or bookings. What can I do?

Nine times out of ten it is the profile rather than the message.

Work through these in order:

1. Add media. A recording is the single biggest thing. Someone deciding whether to book you wants to hear or see you, not read about you. See adding photos and media.
2. Fill in your fee range. Without it, bookers cannot tell if you are in budget, and many will skip rather than ask.
3. Update your availability. If your calendar is out of date you will be filtered out of searches for the dates you actually could play.
4. Finish the basics — photo, bio, city, genres. See editing your profile.

On messages themselves: be specific. A short note naming the venue, a date you are free and a link to a track gets replies. A generic "any gigs going?" usually does not.

Build up reviews as you go — a profile with a track record is a much easier yes.