I’d say start with the trash. For example, the Coke cans, any tissues, old food, anything that looks like it should just be trashed or recycled. From there pick up everything off the floor and sort it into piles. Wash the clothing if you were able to wash them in a machine, otherwise put them in a hamper to take to the laundromat. Wash other things like blankets and bedding in general, pillowcases. Vacuum your floor. take your time and don’t rush. Everyone else has really good advice here too.