It's really not that difficult: As a Buyer:
1. Pay as quickly as you can, if you have a delay in paying, tell the seller immediately. Sometimes they will work with you, sometimes they will have to move on to their next buyer; it's not personal, remember that.
2. Do your due diligence. Find out whatever information you need prior to the transaction. Asking for a phone number (and calling it to verify the user) is perfectly reasonable. Asking for their SSN/Drivers License may be a bit much.
3. If it seems too good to be true, it is.
4. ASK QUESTIONS! If the sale said "shipping included," don't assume it includes insurance, or that the person knows about how to ship overseas, or anything else. Asking these questions FIRST solves those issues, and, if there does end up being a problem, you have some (not guaranteed) protections in place.
5. Don't be afraid to walk away. Deal starts changing after the "sold" label goes up? Seller now wants fees covered? Pictures don't match? These are red flags, if you can't resolve them, walk away, it just isn't worth it.
6. TANSTAAFL. There ain't no such thing as a free lunch. People are selling stuff to MAKE MONEY. Go into the transaction with that understanding. Don't think that you will be able to get that $5 part with shipping included unless the seller enjoys taking a loss. After the packaging and driving to the shipping location, the seller would be losing money.
7. Be civil, be polite, proofread your messages/posts, READ and understand what they write back to you. I've seen a number of transactions go sideways because neither side took the time to understand
what the other was saying. Along with that, we have a good sized (and growing) non-native English speaking user base. Have some consideration for that. Being a dick about it doesn't help. Ask for clarification.
8. Don't badger. Did you PM an offer to a user, or leave it as a post? Did you get ignored? Chances are the seller isn't interested, or accepted another offer before seeing yours. We're not trading kidneys here, you won't die if you don't get that right-feed dingle flipper, just move on to the next one. If you just paid at 10pm Friday night, don't expect the seller to have shipped by 7am Saturday morning. A lot of Post Offices are having their hours changed, sometimes without warning. The seller in this case may not be able to ship until Tuesday, again, you won't die if it's not shipped as soon as you pay.
9. Feedback. It's important, use it. Good, neutral, bad, if the seller cares at all, they want to know how the transaction went for you. (personally, I consider each time that I'm not left feedback to be a "negative" feedback, but I'm critical that way,
10. Be clear in your payment what it is you are buying. PayPal doesn't crawl the BST for your username. They have a comment section for a reason, use it. (I like to write something along the lines of: "This is payment in full for xxx item, as agreed to on forum yyy from username zzz." I then try to remember to include my email and phone number if they need to contact me. The seller will thank you for it. As a Seller:
1. Be clear in what you are selling. Ideally, your pictures should be of what you are selling, not "this, but without this, this or this, and now with this" Take a picture of what you are selling. Along with that, try to take a decent picture. Even the camera on a cell phone is good enough, if you set up the picture well enough. Lighting and background are key. Take the extra 30 seconds, it will result in more interest and getting a higher price if your buyers can see
what it is you're selling!
2. Pay attention to the forum rules, things might be a little different at each forum you sell at. Learn the rules. A thread that has been "moderated" is less likely to get a good sale as buyers see that as a red flag. You might not agree with them, you may think they're silly or overbearing, but the fact is, it's the forums ball and field, and you're a guest, act accordingly.
3. Be polite. You may get criticism for your price, your pics or whatever. the only prober response is "Thank You." You may flip your computer screen the bird, throw things or yell at your girlfriend, but don't let it out in your response. If someone goes overboard in your thread, report the post, include a clear description of what is going on and what you would like done (usually delete the post), and let our mod staff deal with it. That's what they're here for, among other things.
4. Communicate. You are not a retailer. You should be able to ship things in a reasonable amount of time. If that can not happen, tell your buyer. They may ask for a refund, they may be cool with it. Not telling them is a good way to piss them off. Adult communication goes a long way. If you can not find a part, you should have thought of that before posting the sale, talk to the buyer to see what they want to do.
5. Do your due diligence. Just like the rules for the buyer. They provide an address, look it up in Google Street View. If you see an apartment building, and they didn't provide a unit number, guess what? You need more information! Ask them for it. Again as a seller, don't be afraid to walk away if you feel a red flag is waving, someone else will want what you're selling, probably.
6. Use feedback. Both to look up the other parties history, and to add to it. Don't be afraid of issues, except for the ones you don't know about until a month later when the buyer is bitching about something they bought from you saying it isn't working right. If they bring up a legitimate issue after receiving the unit, work with them to a reasonable point. Some people will try to pull something over on you. Work with them to the point you are willing to go, but set your limit. You're not selling stuff to pay back someone who thinks they have you over a barrel.