Im not a bad person, I have raided and griefed. Most of everyone has. Here is how they do that.
Usually I always find a target, someone not on all the time, or someone not a staff. I try to go to their house somehow. Either by teleporting there (with /tpa) or walking there. Once I have gotten there, I either set a home there or stick around until they leave.
I am not sure how others do this, but I believe very close to how I do this. If you have done this, comment below how.
After they leave, I take everything valuable. If sethome is available, then I will do it efficiently. Without it, I would just take it and run. I take as much as I can, and if there is a Backpack mod on the server, I will use it.
Now that was raiding. Griefing is different, but I usually never greif unless there is a rare block.
Here is the thing, if the base is unclaimed on some servers, their fault.
After that, now becomes the "police search". They come on and complain about not having their stuff. I usually keep silent or even help. Some servers have plugins that show what edited what. Some servers dont, and I get away clean. If I do get caught, I either return nothing, something, or make up and excuse.
Common excuse is "my sibling did it". Here is the funny thing, I do have a sibling, and he knows how to grief and raid. He has been on servers before and griefed entire homes.
Going under the radar is dangerous than being like "hey yo I did it lol just a prank can be mad". Sometimes I get away with it, sometimes I don't. A staff will be questioning and most of the time, come out true. If my sibling did it, I usually say to them I have a sibling. Most times, they don't believe me.
Another problem is staff that snoop in bases, and I hate that. They might notice "hey! Look at all this stuff that appeared here" they say.
I'm the total opposite of you, for I enjoy griefing and raiding and thus do it multiple times a week. Usually, I find the targets by using the /randomtp command and then do /f map to find nearby factions. Factions are oftenly unused chunks of claimed land, but sometimes you'll be lucky and get an actual base, bonus points if it's in the open.
As for how I grief, there's a very nice /shop command that lets you buy things. I have a passive income of $40k a day, so I can easily afford tons of stacks of it. Then the fun finally begins! If it's a claimed land, I have to build a TNT cannon in order to break in and steal from chests. If it's unclaimed, then I firstly raid the chests then blow it all up.
The /tpa strategy I don't use though, as many players are paranoid of letting someone /tpyes - It's a factions server after all and people may easily sell coordinates of popular factions for lots of money.
And that's how I raid and grief! It's a great way to get resources but bannable on some servers (a lot of survival servers can ban you but I've never seen a faction one)