Are you male or female? My experience (as a guy) is that you will need to send out a very large number of emails to get a small number of responses. From talking to women, their experience was the opposite - they get deluged with lots of emails and have to filter out a lot of garbage to find the few worth responding to. So don’t get discouraged!
Be very honest about the sort of person you are and what kind of person you are looking to meet, as well as what kind of a relationship you are looking for (friends, dates, want to get married soon, etc).
Have some recent photos of yourself. A lot of people have had the experience of meeting someone only to find that the photo was ten years old and a lot has changed in that decade.
I found online dating to be kind of “meh”. Some dates, some no-shows, at least one blatant gold-digger, nothing really came out of it.
OTOH one of my best friends met his future wife when she took a chance and emailed him out of the blue (they lived 400 miles apart at the time).