1. Get Pre-Approved for a Home Loan
I've known sellers who signed a contract to sell their house before they knew if they were qualified to buy another. Either their financial circumstances had changed since their last purchase, and they could no longer qualify for a loan, or they weren't able to sell at a price that allowed them to buy the type of replacement house they wanted. They ended up renting or buying something that was far from ideal.
Before you decide to sell the house, get pre-approved by a lender you trust and research the housing market in the area where you wish to live so that you have a good idea how much it will take to buy a replacement.
Start looking for two types of real estate: houses that seem to match the one you'd like to buy and houses that are similar to your current home.
How do the two categories compare in price? Can you handle the difference if you're planning a step up?
Mortgage Helpers: Are You Pre-Approved for a Mortgage? And to compare for-sale homes to your own, learn how to Measure Residential Square Footage.