If you are a seasoned reseller, one of the biggest tips out there is to stay consistent and cross-list. Each platform has pros and cons. Some apps will grant you access to cash fast, some have waiting times, some hold your funds until a good review is posted. The important key is to figure out what works for each application. For example, high quality clothing items do great on Poshmark. I use Mercari for discontinued perfumes, lotions, and toys. Facebook Marketplace is easy to sell locally for cash with no fees. Offerup releases your funds as soon as you ship before the buyer even receives it.
Find your niche and get hustlin!