How to Attack a Base in Minecraft

Preparing

Take any wolves or ocelots you might have. Take the strongest dog(s) and ocelot(s). If they have low health, they may need to be fed the appropriate meat. Check the tail to determine if they are low on health. If the tail is high up, they have full health, but if the tail is down, they have very low health. Dogs basically accept any meat, even Rotten Flesh from Zombies. Ocelots must be fed fish.

Get a friend to go with you. It could lessen the time of the raid and do more damage. A group of friends is even better if there are people guarding the base.

Bring a good sword, TNT and good tools. You should bring rails (if you can bring your loot to base that way) and minecarts with chests to take immense amounts of stuff. Potions will also be useful as you could get into a fight.

Gather armor. Bring enchanted Diamond armor if possible. Ideally, the armor should be fully enchanted.

Take a closer look. It could help you to recognize the house and terrain. You might need to look at a map to plan your attack. An alternative is to ride to the base and scout from high up in the air, whether a mountain or literally high up in the air. Ride pigs, horses, or an empty minecart. You could also stand on a Ghast or other flying creature to get an aerial view of the base.

Get on top of the base. This can get you a good at look at defenses and sentries. You can either blow yourself up there with TNT, use a Slime Block as a trampoline, or build a bridge from another mountain. This is a pretty unsafe method, as players in the base can see your name and know you're on top of the house.

Have good timing. Go at dark. This is the best time to raid because your enemies can't really see you. You can also use mobs for your advantage while raiding.

Outside the Base

Kill the person defending the base. He will be weakened, and you could get his/her weapons and their armor. You should do this from far away. If you get close up, you have a greater chance of dying, and if you do die, the guard can warn the people inside, and your whole raid could be ruined.

Intimidate them. Send Ghasts, Ender Dragons, Wither, Giants, or Zombie Horses outside the base. This might not be the best idea if you're looking for the element of surprise, because some of these enemies (Ender Dragons, Giants, and Zombie Horses) must be summoned, and the command appears in the server chat.

Destroy the walls. You could use cannons, TNT, or even a creeper.

Enter the base from underground. You could dig a tunnel underground, and then end up right in the middle of the enemy's base with the element of surprise. Use rails and minecarts to quickly traverse underground.

Enter the base and start the raid. Make sure that you are ready to fight if needed and have enough inventory space to loot items you want.

Inside the Base

Use TNT and flint and steel frequently. This is especially effective if the house or part of the house is wood. If you do this, make sure you can get out safely!

Use wolves. If anyone hurts you, the wolves will instantly attack them. One man doesn't stand much of a chance against three wolves.

Use enemies such as zombies, zombified piglins, or wither to your advantage. Make sure you know they're not going to turn on you!

Use Iron Golems and Snow Golems to your advantage. Iron Golems would probably be best. They take more damage when attacking, and also have more health.

Split into groups. If you're playing on Multiplayer, you can have one group raid the house, and one group hold off any enemy in your way.

Make sure to take everything valuable. Destroy everything in your path.

Kill any animals the owner of the base might have. They create resources such as eggs and milk.

Destroy water sources.

Destroy any beds the owner might have. This way, if they die, they can't respawn in the house.

Maximizing Damage

From the roof of the house, pour lava or water in. However, make sure to evacuate your troops!

Seal off entrances and exits with obsidian once your troops are out.

Make Redstone traps, such as dart traps or spear traps, to kill owners in the base.

Use silverfish. These little guys burrow in random blocks and hide until that block is destroyed. Once it is, they are released and are very hard to kill. This works extremely well with the obsidian trap method because with all exits blocked, the owners will have to destroy blocks to get out.

Bring stuff to help you heal. This could be rabbit stew, potions, or any type of food item.