If you're looking to sell your IPv4 addresses, there are a few things you need to keep in mind. 

First, you need to make sure that you have a market for your addresses. There are a few ways to do this, but the easiest way is to use an IPv4 broker. Once you've found a broker, you need to negotiate a price. This can be tricky, as there are a lot of factors that go into pricing IPv4 addresses. However, if you do your research and know the market value of your addresses, you should be able to get a fair price.

Once you've agreed on a price, you need to make sure that you have a contract in place. This contract should spell out the terms of the sale, including the price, the number of addresses being sold, and any other relevant information. Without a contract, you could run into problems down the line.

Finally, you need to make sure that you follow through on your end of the deal. This means transferring the ownership of the addresses to the buyer and ensuring that they can use them as they see fit. If you don't follow through, you could damage your reputation and make it harder to sell addresses in the future.

By following these steps, you should be able to sell your IPv4 addresses without any problems. Just make sure that you do your research and understand the market before you agree to any sale.