A happy new year to you too and welcome to SaleHoo!
For beginners, we would usually suggest you start by selling things you find around your home, like old stuff you are not using but are in mint condition or something you never used. This way you don't need to invest anything for capital and you get to practice the ins and outs of selling online without worrying about your losses.
Here's something you can do to check what products are selling well on eBay:
1) Check out the popular searches and most popular products on eBay:
Popular searches: Link hidden: Login to view
Best selling products: Link hidden: Login to view
eBay pulse: Link hidden: Login to view
2) Perform completed listings searches for products or brand names to see the conversion rate and average selling price.
To do a completed listings search, simply click the Advanced Search button next to the main eBay search box. Enter your search keywords as usual, and then check the Completed Listings box. Hit search and you'll see historical data for the previous 30 days. Successful items are in green; unsuccessful items are in red.
Hope this helps. All the best! :)