There are 2 types of second mortgages, a home equity loan or a home equity line of credit (HELOC). The first type loans you a large sum of money up front. You make regular payments with a fixed interest rate to repay the loan, according to the mortgage terms. The HELOC, on the other hand, usually has an adjustable interest rate, and similar to a credit card, lets you borrow money as you need it.
Second mortgages involve the same amount of work as the first one, including home appraisals, disclosures, paperwork, and a number of fees. It is not necessary for the second mortgage to come from the same lender, either; you have the option to go with a different mortgage provider. So you will have to shop for mortgages the way you did before, in order to get the best deal.