As much as I hated it, working as a cashier at a local grocery store would be a good start. It helps you with social skills, and also makes you realize that you will never want to work at a customer service job in your life. You earn enough to make some cash, you stand all day long so if you're tall (I'm 5'10) your back is gonna kill you by the end of the day due to leaning over to pack bags and stuff, and it can get kinda stressful when things pick up but overall it was a good experience. If you can, go for a job like produce, so you don't have to deal with customers as much.