A good announcement answers five questions in the first three lines.
And the question everybody forgets: when it finishes. People are planning an evening and will not sign up if they cannot tell whether they are free by nine.
What kills an announcement: the word «competition» instead of «tournament», a rating requirement, a missing address, «come and play» with no detail, and most commonly of all, no line saying that the standard does not matter.
The reminder the day before is the most underrated step. People sign up a week ahead and genuinely forget; one message lifts attendance far more than announcing earlier would.
A first tournament gathers strangers. The second and every one after live off the people who already came - provided the organizer gave them a way back.
In local chess chats and clubs, through coaches at schools and clubs, through the venue itself, in city listings, and in adjacent communities of board games and quiz nights. From the second event onwards the main channel is your own previous players.
The first announcement two weeks out, a detailed repeat a week out, a reminder two or three days out and a personal message the day before. The day-before reminder lifts attendance more than announcing earlier does.
What, when, where, for whom and how much, inside the first three lines. Plus the finishing time, because people are planning an evening. And a line saying the standard does not matter, if that is genuinely the case.
Do not cancel: an eight-player event is a real tournament and cancelling hurts the format more. Message a few people directly, switch to a round robin for a small field, allow walk-ups, and take photographs - they are the announcement for the next one.
Name the date of the next event before people disperse, run a chat with announcements, send out the final table and build a series with a combined standing. A visible calendar of upcoming events removes the need for anybody to go looking.
No arbiter skills required. The app takes over the part that usually stops people from running tournaments at all: who plays whom in each round and who finishes first.
The bot is constantly improved based on real tournaments. If you need a feature that isn't there yet, message the developers right inside the bot with the /support command. Many features appeared exactly because organizers asked for them, and useful ideas get added quickly.
Registration - taking entries. Content - photographs from the event. Prizes - the prize-giving. Retention - why people stop coming.