Line a sheet pan with aluminum foil. I typically overlap two or three pieces. 

Remove the bacon from the package and lay as many slices as you can on the foil-lined baking sheet. You can place your bacon very close together but try not to overlap the pieces. If you can't get the whole package on there, put the remainder back in the fridge for later. 

Do not preheat your oven. When you have as much bacon as you can fit on your sheet pan, place it in a cold oven and set it to 400 degrees F (204 C). 

Set a timer for 20 minutes and start checking the bacon. Depending on the type of bacon and thickness, it could take another 5 or more minutes. 

I start checking at 20 minutes and if it's not fully done, I will flip the bacon and put it back in the oven for another 5 minutes or so, checking the doneness every so often. Once the bacon is done to your liking remove the slices to a paper towel-lined plate and store in the fridge if you're not using it immediately.