We're in a throwaway world. Things like furniture sell for very little on ebay unless they are real antiques or very upmarket. You can check typical sale prices by checking in the left-hand sidebar, search for your item type and check Sold in the sell column. Prices in green are what has actually sold, red are where it hasn't. Lots of disappointment there. Try following a few items similar to yours, click Watch Item, no obligation.
Allow for postage and a bit more for packaging. If it's collect only, and furniture will be that, it will depend where you live. If you're near a big population there will be much more chance of shifting stuff.
Take good photos, preferably in daylight. Especially for clothes, daylight will show the colours accurately. You get up to twelve pics per listing, use them.
Write an accurate description, there's no limit to word count. Add info there re any extras, eg that you have other similar items and will combine postage. Check the boxes in the initial setup in as many categories as you can. Choose your heading description carefully, that's what people search by.
Think about how long to list for. I usually go for the 7-day option. Also when does the listing end? Something where the bidding ends at 3 a.m. will put off last-minute bidders. I usually time things for Sunday afternoons. You can adjust the end time as you do a listing.
It could be that for some things it's just not worth your time. So then it's charity shops. There's also Freecycle, or Freegle, where you list stuff you want to give away. It then goes to someone who can actually use it rather than gathering dust on a Oxfam shelf. Can be frustrating if people don't turn up when they say, get phone numbers from any who want stuff so you can chase them.
Car boot?
Good luck.