Most sellers will not reveal their secrets (if they did, it would no longer be a secrete).
You are in competition with everyone else so you will have to find what is best for you through trial and error.
One thing you can do is try selling things from around the house like CDs or DVDs you no longer want.
Do not believe those "get rich on ebay" scams such as the ones that appear on late night television.
Don't use dropshippers. They are the only ones who make the money while you do all the work. Additionally, in order to make a profit with their products, you would have to sell the item at or close to retail and almost no one will buy if it is the same price as a physical store.
Use your own pictures whenever possible especially if the item is used.
Not everything sells on ebay as you have found out. Something may be worth buying to you but of no interest to others. Sometimes it may take several relists before an item sells. Summer time is notorious for slow sales.
Somethings sell better during a certain time of year.
Some people buy from yard sales and thrift stores then sell the item on ebay.
Research completed listings if you can to see if an item is even worth listing. I would get these bright ideas about buying things from the dollar store only to discover about 100 other people were selling the same thing and very few, if any, were being sold.
Keep trying until you find what works for you.
Non paying buyers deserve unpaid item strikes.
