I do a 3 bin system made from recycled pallets. They’re 4 foot square each. I try and turn the piles at least every week. Now, food scraps, i keep out and use the Bokashi method in a big bucket. I let it break down in there then throw in my pile when I’m turning it. I don’t have any issues with rodents. Maybe an occasional Opossum but they’re going after the bugs. The system you need all depends on how much browns and greens you have available. I have a sizable garden and giving neighbors. Go bigger than you think you need.