Strategy in Killer Queen Black is not only highly situational within a match, but also shifts depending on the kind of players you are playing against.
The strategy here, particularly with respect to economic and snail victory conditions, is really geared towards beginner and intermediate level players. As your skill and your opponent's skill increases, you will find that different tactics are needed.
The Queen is the highest responsibility role. The choices you make will have a big impact on what your teammates can and can't do. Not to mention, you yourself are now one of the three objectives.
Now that killing you is one of the game's objectives, you need to stay safe. That doesn't mean cower in the hive, but it does mean not taking dangerous chances needlessly.
So, how to not die?
Arguably the queen's most important job is to make sure your team's workers can upgrade to warriors. This means two things:
Take care of your workers, so they can take care of things for you.
In terms of offense, your focus should be first killing enemy workers before they have a chance to warrior up (watch those gates), or when safe, kill warriors you weren't able to stop from upgrading.
Also, tagging gates isn't just about getting your own warriors up. It's equally important to tag gates to prevent enemy workers from upgrading to warrior.
This is related to all the above points. If you spend the whole match just chasing the enemy queen around, you're more likely to die, you won't have time to tend to your workers, nor pick on the enemy team's workers.
Workers have two distinct roles: vanilla worker, or warrior (aka soldier aka military aka "mil").
There's three of you, and you need to decide whose going to be taking on which worker roles, and which objective you will be pushing.
This is where Voice Chat is critical and the start of the match. Use voice chat to decide who is going warrior, what kind of warrior, and if you are going berries or snail to start.
Alternately, use Alerts and Emotes and pray your teammates get the message.
Broadly speaking, Berries are the strongest objective to push. Don't underestimate them.
Learn to throw berries into the hive, rather than just running them in.
Throwing berries save you:
There are two kind of berry throws:
Try going into one of the game's tutorial levels, and practice your berry throw tech there.
Note: Berry throws can be risky on some maps, as you could throw a berry into the enemy hive.
As a worker, you are extremely vulnerable. But you do have a secret defensive weapon to staying alive, Cooldowns.
Worker cooldowns in this context are temporary invincibility frames (iframes) after taking an action.
The cooldowns are: