Hello, everyone. I will teach you how to create a slime farm with ease with the following instructions. You can do these right away after beginning a new world. I do these on the Xbox version but they can be done on the PC as well.
Here's how:
1) Create a 3x3 hole, descending on a drill formation.
2) Around the 3x3 hole entance place a 5x5x3 "survival hut, equipped with a bed, crafting table, and furnace (also place a chest were you think that it should be comfortable.
3a) Stop mining until you reach bedrock. Once you reach it cover 3 blocks upwards were the bedrock was.
3b) If you find a cave or a ravine, patch that with wood, or start all over. If you find a fortress, abort plan (start over) and mark the place as important.
4) Make cobblestone stairs for better access in and out the farm (cave).
5) Start mining a 50x50x3 "Slime farm" and place some chests and furnaces on the entrance. Here you will gather enough cobblestone to create a mansion (along other necessary resources). Without an Iron or Diamond pick, this will easily take 2-3 hours (mostly 3).
6) Each time your inventory maxes deposit cobblestone and other resources on an organized matter in the chests.
7) Lava may come out in some areas, so quickly stand looking towards a solid near the lava area and block it's path (repeat this until there's no more lava).
Enchanted Diamond Picks with Efficiency3/Durability3/Fortune2 (or 3) will greatly speed up the process (finishing in 1-2 hours).
Benefits of Slime farms? The Slimes, of course, and the resources obtained along the way. These caves can hold up to 30 Diamonds (and trucks full of Diamonds if you have the previously mentioned enchanted Pick).
P.S. Once I'm able to play Xbox again, I'll make a sped up tutorial for the visual benefit.