Selling on Craigslist is very straightforward... it is posting like in a blog... you have to make sure your post is in the right category or it may get flagged and removed... more about that later.
So you have picked your category of what you are selling or giving away... you have your picture ready... a bad pic is better than no pic ALWAYS!
Now for your title... which automatically opens when you choose a category. Your title should >>> Stand out <<< from the crowd some. Use ALL CAPS when you want to catch attention to ONE detail... don't use caps on your whole title... it is overwhelming and people will skip over it.
Next decide how much you want to sell your item/stuff for. It will not take $0 if it is free... just leave it blank. If you later change your price the first price you enter here is the one that will show up when people visit the page about your item.
Next enter the city or area you live in so people will know if they want to drive to you... so if you live in one city but work in another and want to sell it from your work area... give that city in this space.
Finally write a description and make sure to use key words that people might look up in the general search engine. We sell lawn mowers... so I make sure to say the name the size and push mower or riding mower. Always give as much information to help the buyer make an informed decision and have a picture to post so that people don't show up or show up but leave without your item.
We call our buying and selling on cl "adventures". We have met many interesting folks along the way. But giving away free stuff is still my favorite thing. I love giving something to someone that couldn't afford to buy it... leftover vases, junk I wanna take to goodwill... put it up on cl for free and watch the magic happen!