When trading, do not be in a hurry as trades can generally happen pretty fast. You get excited as someone has your "Holy Grail" and you tend to skip the essentials... such as checking references if you do not know the person. Slow down and don't fret....take it one pin at a time!!! If this trade does not go through another might just be around the corner. 
 

Respond to EACH AND EVERY e-mail you receive....whether you are interested in the trade or not. A quick reply e-mail saying "No Thanks" can make a big difference in establishing yourself as a Good Trader and more importantly, it is a common courtesy. Generally speaking, if I do not get a response within 24 hours of my e-mail to the potential trader, assume that the trader is not interested. If you wish to counter the trade, reply back with "I wish to counter this trade with the following pins..."
 

Know your pin and its value. Ask for references, if you do not know the person. (BEWARE: AOL can have up to five names on one account). You can check the Dizpins Reference Center as a start for checking references. As many traders are registered users on eBay or another auction site, that is a good place to also note references. If a person does not have that many references, ask that they ship first or you can mail your pins to a third party who will then mail the pins to the respective recipient. Any of the Dizpins or Pinpics Moderators will be glad to assist you in a Third Party trade. You will, of course, be responsible for the postage costs for the third party. If they do not have references listed, such as those on eBay or another auction site or in the Dizpins Reference Center, ask them for names and e-mail addresses of other persons they have traded with and follow up and e-mail for the references. Do not commit to the trade until you have checked all references, if applicable. If I did not mention it enough yet, always remember to check references!! 

A third party trade is where both parties mail their pins or the money if they are purchasing a pin to a Moderator. Upon receipt from both parties, the Moderator will inspect the pins and send them off to the parties involved.

Any Moderator on Dizpins or Pinpics is happy to help out with this and you can e-mail Dizpins or Pinpics for help.  

Discuss how each of you will mail the pin. I prefer to mail First Class. Depending on the pin, especially the value and rarity of the pin, insuring the pin for a few extra pennies can put your mind at ease if it should get lost. You can also use Delivery Confirmation, but be sure that the package is at least 3/4 of an inch think, or the recipient will be responsible for postage due, which is the difference between first class and priority.   

Confirm the trade in writing.  Send an e-mail to the trader stating that "This will confirm that I will send you "such and such pin" for your "such and such pin".  Wait for a returning confirmation from the trader acknowledging and confirming the trade.

Properly package your pin. Your pins should be protected in a little baggie and/or tissue and then wrapped in bubble wrap. The pins should them be place in a bubble mailer to insure added protection. Under no circumstances should pins be mailed in plain, unprotected envelopes. 

Mail the pins out when you say you will. If by chance you do not mail on the day agreed upon, notify the trader of the delay. 

Make sure you are clear on what pin you are trading for and what pin you are offering. Ask questions. Clarify. Use PinPics to ascertain the EXACT pins that each of you have to trade. 

If purchasing or trading, ask the seller or trader about the condition of the pin. If you ask before it arrives at your door, there should not be any surprises. Make sure you ask if the pin is MINT and that there are no scratches, dings, etc.

Go with your instinct. 

Get a phone number and give your phone number. This way, if the "puter" is having problems, you can follow up on the trade. 
 
If a trade is "TOO GOOD TO BE TRUE" it probably is... You are either not going to get exactly what you think or you might be getting nothing at all. 

If you agree to purchase a pin, print out the e-mail that you get from him/her stating the amount for the pin and write your name and mailing address on that paper. Then fold it up and include it with your payment inside the envelope. When the seller gets your payment, they will know which pin goes to you. This may not seem important, but some sellers deal in volume. 
 
Keep good records! Keep track of when you sent your pin and keep all e-mail correspondence that you have with your trader. If you haven't received your pin in a reasonable amount of time from the trader, e-mail them and politely ask the status of the trade.  Get the trade agreement in writing, and confirm the trade by exchanging mailing addresses. Keep the trade agreement until both parties have fulfilled their trade.

Do Not Assume that the pin comes with the extra frills. A normal trade agreement is for the pin. So if the pin you want comes in a box, special backing, or a display card, please verify that the other trader is sending you the special items.

If you are a trader who feels you must receive the package before you ship yours, this is rude pin behavior. By holding the pin "hostage", this conveys the message you don’t trust the other person. The Moderators do not approve of this practice and will not tolerate this if a complaint is made against you.

Each trader is responsible for their trade until their package reaches the final destination.
Do not use a common #10 paper envelope. Ship the pin(s) with foam, bubble or padded packaging. You can buy the bubbled size #00 or #000 envelopes at an office supply store, or online stores or even ebay.
If the pin is fragile, consider using a box instead of an envelope. Add insurance if the pin is irreplaceable.
The package is the responsibility of the sender.

If you are trading a hard to find pin, or a pin which is not replaceable, spend the extra money and use a tracking service like deliver or signature confirmation. For international traders, send it by Registered Mail, which is the most secure method of shipping.

Occassionally a problem may occur. If there is a problem with the trade, try resolving the issue in a polite and profesional manner. Remember that as a member on PinPics and this trade was made through Pinpics, you agree to the Term of Use as found http://www.pinpics.com/legal.htm

When you receive the pin, inspect it carefully. This is the time to notify the seller/trader if there is a problem, not two weeks from now. If the pin meets your expectations, let the seller/trader know! Advise them that you were pleased with the sale/trade and you can also ask if they have any more pins for sale or trade!!!   You can also mention to them that they can use you as a reference for new customers and leave them a comment on a good traders list, if applicable.   You can also leave references on the Dizpins Reference Center.
 
If you are not satisfied with your pin, politely e-mail the seller/trader and explain why and propose a way that the situation can be rectified. Perhaps they can offer you a partial refund or if you absolutely do not want the pin, ask how you can return it to them for a refund or exchange of the trade. The important thing here is to be polite and professional. The nicer you are, the easier the rest of the transaction will be for you. 

If you find you were involved in a BAD TRADE or an alleged bad trade, there are a few alternatives that you have. One is to use a mediator to try and resolve the issue. I have moderated many potential bad trades and usually an e-mail or two may rectify the problem. You can use the Pinpics and Dizpins Universal Trade Reporting System.

Mail Fraud Complaints need to be filed with your Local Post Office, and here is the form that they will need: US Postal Service Mail Fraud Complaint Form.

Finally...Communication is the Key to a Good Trade. Communication from the start of the transaction to the end. More importantly, e-mail your trading partner when the pin arrives so they will know that you have received the pin and of course, to say Thanks!!