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:
From having running into/out of the hive
Animation time of crawling into/out of hole in the hive
There are two kind of berry throws:
Some maps are set up that a few holes you can stand on a nearby platform and throw a berry right in with no momentum.
Most throws will require you to build up speed and use your momentum to transfer that energy to the berry toss. Your jump angle determines the direction the berry will go on.
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.
First off, don't be discouraged if you're dying all the time as a drone! For an ordinary worker, the consequences of dying are measured in seconds. Your objective is not to avoid dying at all costs, but to make it so that the enemy wastes more time killing you than you waste by dying.
Learn to read the movements of opposing military. Over time, you'll find that enemies tend to attack you with similar angles and timings. Use that information to avoid attacks.
Jumping on (and bouncing off) the heads of attackers can be an effective way of making yourself safe. Not even the queen can attack someone right above her!
Situations may arise when the other team has full military and your queen can't protect you. In this situation, it's your job to be hard to kill and to draw attention away from your queen for as long as possible.
Shields can be valuable if you can learn to bump away enemy military. When you bump into someone with shield, you won't get pushed back -- but they'll get bumped around twice the distance. Bully the opposing military!
Knowing the cooldowns of attacking warriors and queens can help you understand when you're safe and when you can be attacked.
A warrior's role can change frequently throughout a game. Always be aware how the opponents are trying to win, and how close you both are to victory, when deciding what to do as a warrior.
Guarding an enemy hive to defend against economic victory. Depending on your weapon and playstyle, you can block the opponent's berry progress by body-blocking shots (typically as mace), hunting enemies in and near the hive, and pushing loose berries away from the enemy hive (and towards your own hive)
Protecting another player -- this is most commonly used to help a drone run the snail by clearing out the opposition and threatening anyone trying to kill your snail=runner.
Having more warriors on the board restricts the opposing queen from moving freely, especially if she has few lives. Chasing the queen away from her goals and trying to trap her in bad positions can allow your workers to reach their win conditions -- or can end the game with a military victory
Countering the opponent's military pressure by taking down their warriors. If the opponent has a Ledge preventing your workers from getting their berries in, you can fly up and attempt to clear them out. Similarly, you can clear the warriors around the snail to prevent the opponent from winning.
In-Depth Warrior Tips
Swords have the greatest mobility of the warriors and excel at chasing away opponents and controlling tight horizontal spaces.
To stay alive, get your spacing right! Get a handle on exactly how far a dash attach will take you, and always be SLIGHTLY further than that dash attach range from other swords and the queen. Wait for them to dash at you and hit them after they miss for an easy kill!
For a more aggressive strategy, try to dash down at the opponent so your sword hits their head. Maintaining the high ground can provide you with an advantage when you clash.
Maces lack the burst-mobility of the sword, so they rely on spacing, angles and timing to stay alive. Your ability to succeed as a mace hinges on your capitalizing on your opponents' mistakes. Position yourself away from the business-ends of other weapons (straight across a warrior, under a queen) and float in for the strike!
The mace is very threatening with diagonal and vertical movement -- get a dash to miss above or below you and you'll likely get a free kill.
Maces can also score kills by retreating and moving unpredictably. Stay just out of reach of a warrior or queen's dash attack -- your kills will often comes from your opponent getting impatient or taking a bad angle. Be ready to time your spin to
Be aware of the mace's spinning direction! It will always start in front of (and slightly below) you, around 4:00 facing right and 8:00 facing left. It will also always move down first, meaning it'll spin clockwise facing right and counterclockwise facing left. This leaves you vulnerable to attacks from the front when starting your spin! See :22 on this VOD for an example.. A good tip because of this -- face away from your opponent when starting your mace swing.
Maces control space. Use that to your advantage when queen hunting -- if a few swords or your queen are chasing the opposing queen across the map, float around an escape path to limit the opponents' options.
When in combat, try to be running away from people chasing you, bobbing up and down with unpredictable horizontal movement. This will maximize the odds of the attacker killing themselves on your mace, rather than hitting you.
With its long range, the gun shines at controlling horizontal space just by existing -- opposing queens and warriors have to respect your ability to lock them down if they stray into your attack space.
Be careful when you spawn: enemies will likely target you heavily, and your weak mobility can make you easy prey for queens and swords. Try to fly to your military for protection.
Save your shots! Gun warriors have a lengthy reload (which is sped up dramatically with a speed upgrade), and if you're empty all the time you're often not going to be able to get that snipe on the opposing queen. Control space by threatening to shoot!
If you're looking for a queen kill, hang out in vertical wraps and shoot from directions the queen can't expect.
A dashing warrior will outspeed you horizontally, but can't fly or fall faster than you. Escaping vertically can give you better survival odds.
If you're on reload, try to stay away from unsafe, highly-trafficked areas of the map. It's easy to tell when you can't make a shot, so hanging around where you can get killed won't do your team any good.