There are any number of sites out there that give you advice on how to create your own eMail signature and even offer services to do it for you – it all depends on what you are looking for when it comes to this side of things.
I follow a lot of what DigiTechBranding tells to do in their guide mostly because I’ve found that it does work for what I’ve dun over the years as email has evolved.
With the world as it know it changing and going more mobile email signatures vary greatly some people use them and other’s don’t but most larger companies to have them and use them so it does make sense if you are a small business that you also have such a signature for when you are sending out business email and even when you are not doing so, just to plug you business to all who you are connecting with doesn’t hurt.