The thing that AMCs have done is establish connections with the lenders that use them and secure work from them. There is a lot of mortgage work that does not go through AMCs. The key to getting non-AMC lending work is to establish the same kind of connection with those lenders that the AMCs have established with their lender clients. This involves marketing and research to find how who you need to market to. I would start with your local lenders, as they tend to use direct appraiser engagement rather than AMCs.
If you want to supplement your business with non-lender work, then you have to make connections with non-lenders who are are potential clients. This is best accomplished with a marketing plan, but that is something that is foreign to many residential appraisers, especially those who have focused on AMCs. AMCs are relatively easy to market to - you just sign up to join their panel. Marketing for non-AMC work takes more effort, more time, and may involve spending money on marketing. This is why so many opt to just go down the AMC route.
Some of my most fruitful marketing efforts involved targeting groups like, estate planners and attorneys, attorneys who specialize in real estate litigation, agents (for pre-listing appraisals and tough-to-price properties, residential property managers. I also got a lot of work from local builders and developers. It may also help if you develop specialized skills. I had a lot of success with estate stuff because I developed an expertise in partial interest appraisals after I learned that estate planners often use partial interest gifting to shift the burden of estate taxes.
Litigation work is some of the most profitable, and it is some of the most difficult to break into. Once you land the first one, if you do a good job, then word gets around in the legal community. Divorce and bankruptcy cases are often the first litigation related assignments for appraisers. For that, you can target local attorneys who specialize in those areas.
I cannot emphasize enough how important I think a marketing plan is. Almost all successful business have a written marketing plan and a marketing budget. My experience was that at first the money we put into marketing seemed like it was going into a black hole. Then, things start to click, and after a while money spent on marketing is just a smart investment. There is a saying in Nashville about singers and song writers - it took him five years to become an overnight success. I think it is that way with marketing. It took a while to establish our company in some of the niches I have mentioned, but once we did, the jobs and fees were well the time, effort and money.
I would look at my calendar and my books every month and see how much time and money I had spent on marketing/promoting my company. How many agent sales meetings did I speak at? How many attorney events did I sponsor or speak at? How many business cards did we leave with people? That last one is pretty simple. I know a lot of appraisers today do not even have business cards. We had them and the appraisers were required to pass them out like candy. You never know when you will hand a card to someone and that will turn into hundreds of appraisals.