From my own experience.
Early games are characterised by concentrating on basic manoeuvring and trying to avoid colliding with your own ships or running aground. After a handful of games, basic movement becomes more natural and you can move on to thinking in more detail about your own tactics. As these become more familiar, you can start tinkering with the various upgrades to optimise your fleet for your own style of combat.
The game was not designed specifically for tournaments but there is a guide for TOs and suggested map pack to assist in running an Armada event: https://www.manticgames.com/mantic-games-free-rules/
The recent supplements, Seas Aflame and the Magic Deck, extend the rules and add more scenarios, as well as introducing a campaign system…
It was unfortunate that Armada was introduced as lockdown set in and so there have been few tournaments so far. However, Mantic will shortly be running an Armada event.