Facebook has local listings for selling things. A lot of people use that to buy and sell.
Offer up now is another that has local sales they have apps
Letgo is also pretty popular for local sales, they have apps
The trick to getting things sold quickly is to price them below what the competition is asking for the same thing and then stick to that price. You need to take the time to do the research to see what that item is selling for new and what it is selling for used. Do not judge by what it is selling for on Ebay, those prices are very weird and often astronomically higher than the real value. It is a game they play on Ebay to try to drive the prices up.
Buers are amost always going to ask if you will take a discount on the price, that is just how it is done so don't get bent out of shape or let it make you feel frustrated. Sometimes I just reply with a slightly higher cost than what I was orginnaly asking making a joke out of it. For instance a while back I was asking $325 for a portable fridge freezer and they asked if I would take $300. I replied $350 would go down a lot easier and gave a chuckle. They paid the asking price, they knew it was a bargain but it is tradition to try for a lower price so therefore they did try. Never take it personally or be offended by low ball offers, they are annoying but absolutely are to be expected. Many people buy to resell so therefore they need to ask so they can make a profit out from the item. At least half the initial responses will be from those individuals.
Never tell someone you will hold an item for them. That just leads to lots of frustration with missed appointments. I just tell them I don't make promises because if someone else shows up first with cash in hand I would be a complete fool not to sell it to that person.
Be sure you clearly state that it is a cash sale only and that they must show up with the correct change in hand. People will show up with big bills as a way of trying to get the price lowered when you can't make change. So be very clear about they must have the correct change on them when they schedule an appointment.
Be sure you take the time to clean up whatever you are trying to sell. No one wants to take the time to clean up a grungry item, they don't want to deal with other peoples dirt. This is especially true if you are selling kitchen appliances. Take good photos and take plenty of them. Take the kind of photos you would want to see if you were shopping on craigslist.