Alot of ppl wait until the owner of the base leaves, but most likely the reason they went is to get a valuable material that u wanna steal. So wat i do is dig a tunnel towards their base and mine through a wall then leave the hole. Dig another hole on the other side. Most likely the owber has investigated ur previous hole, so go in the base and explore until u find chests. Get all the materials u want and make a run for ur hole. As long as u have at least 8 hearts u should make it :)
Hopefully this helps someone