This could mean one of two things. The first is you want my contact details, and the second is you want me to accept your contact details. Both options are detailed in this page, and is intended to be as simple as possible. With that said, I will address both options here.
Getting My Details
Getting my contact details is pretty simple. If you are OK with .vcf files, and familiar with how your phone handles .vcf files, then you could go to my .vcf file or page by going https://fsp.cc/vcf. If I have just one .vcf file, then you would get the download directly. If I have multiple .vcf files, then you would select which one you would want to acquire. If for some reason I was to change my phone numbers, I will first create a new .vcf file, and make those changes as appropriate.
Another option for those that the .vcf file didn’t work well for will be able to acquire a more basic contact details that will provide my name, phone numbers, email, and website. This will add to you contacts allowing you to add me relatively easy even without using a .vcf file. You would scan the QR code below for everything.

The last option will be to go to my home page of this site, and enter the information detailed on that page. Unless you are able to copy and paste, this could lead to mistakes though. Obviously, no one is perfect, and there is a chance that you could make a mistake. However, if the above options are not available to you, then this will be the next best thing.
Adding You to My Contacts
If you have a website, then the best way to add you to my contacts is to provide the link to your Virtual Card File. If you don’t have a Virtual Card File, and you are able to download and upload files, then you can go to https://fsp.to/vcf. From there, you would fill out the relevant information that you would want anyone to have. For example, if you are uncomfortable with 8 Billion people knowing your residence, then don’t provide your residence when filling out the form. Once you provide the information, you would then select the Generate button. Your .vcf will download to your computer. You would then go to your website manager or FTP client to upload the Virtual Card File. I would suggest that you try to make the URL as simple as possible to reduce chances of providing an invalid address. For example, my .vcf is located at https://fsp.ws/us.vcf. If you are unsure how to upload files to your website, contact your hosting company.
If uploading a file to a website is not an option for you, then you would need another option to providing your contact information. If you have a website, I would recommend creating a “contact” page, and providing all of your contact information on that page. Once you done that, you would be able to place that URL in the signature of your emails. However, this could lead to mistakes, especially if the recipient is using a device that don’t handle copy and pasting easily. If I was to add your contact information, I will use my computer, and copy/paste the information into my contact manager. This should minimize any mistakes that may happen.