Find five unused things
Look for a hat, old game, tool, small appliance, or anything you can actually sell. Pick one. Take clean photos. Check similar items. List it locally.
The first goal is momentum
I care less about how much you make on that first random item than I care about you going through the process. A real listing and a real buyer teach you more than another 20 articles.
Reinvest carefully
If you want to buy inventory next, use money you can safely afford to lose or reinvest proceeds from a sale. Do not rely on a future sale to cover debt.