Take photos in good, even light — near a window during the day usually beats any indoor lighting. Show the item from several angles, including anything relevant to its condition (wear, scratches, a missing part) rather than just the one flattering shot. A listing with several honest photos gets more genuine interest, and far fewer time-wasting "is this still available, can you send more photos" messages.
Include the details a buyer would otherwise have to ask you for: exact condition, dimensions or size, why you're selling, whether it comes with original accessories or packaging. A complete description upfront means fewer back-and-forth messages before someone's ready to commit.
Search for the same or a similar item already listed before picking a price. Pricing noticeably above comparable listings mostly just means fewer people click through at all; pricing very low can (fairly or not) make buyers suspicious something's wrong with it.
Buyers on classifieds sites often message several sellers about similar items at once — the first one to give a clear, helpful answer is frequently the one who makes the sale, all else being equal.
Confirming both your phone and email gets you a "Verified" badge, shown on your listings and profile — a real trust signal for a buyer deciding between your listing and someone else's near-identical one.
A listing that's been sitting for a while tends to sink further down search results over time. Renewing it (or using VIP promotion, if you'd like it shown first) brings it back in front of people browsing that category again.