@Michael Beur Welcome to the wonderful world of note investing. It's a different animal from real estate investing, but there are a few things you should think about.
1) Particularly in the case of seller financed notes vs institutionally prepared notes (banks, mortgage companies, etc), you will want a good, real estate attorney with a background in loans and foreclosure to review them for you. Buying a note that is not enforceable is a waste of money.
2) You will need to have a Servicer that is licensed in that State (Texas I assume) service the loan for you. There are very few servicers that will handle small portfolios any more. FCI and Allied are two that will do it (no, I have no affiliation or allegiance to either company...I neither recommend or endorse either company). They will "board" the loan, send out statements, send out the TILA letter, make collection calls, etc. The new changes in Dodd Frank and the SAFT Act make it so you really can't collect for yourself any more. Unfortunately, that is the way of the world these days.
3) Regarding licensing, which several posters will jump all over on this blog, you will want to call the State's department of Banking and Finance to ensure that you don't need special licensing to buy or sell notes in the State. Some States do, some don't. We don't currently do anything in TX, so I can't answer that question for you, but you can make that call and get the skinny. Don't get discouraged by some of the posts you will read regarding licensing. Many seem be credible, but do your own homework and check into it for yourself. It can be done.
4) You may want to think about getting a partner involved that knows lending. Most people that buy notes have never made or collected a loan in their lives. I was recently on a panel at a large conference with other Fund Managers that buy loans and, to my surprise, most of the Fund Managers had never underwritten a loan in their lives. As I mentioned, it is a different animal. Someone with a strong background in lending, loan underwriting, and collections might be a good person to help you review and select the notes you buy.
5) You make your money on notes, just like in real estate, when you buy the note, not when you sell it. Pricing is critical. Bidding too low for notes will simply make you appear to the seller as being "not serious". Bidding too high and you will loose your shirt. We price based on the quality and value of the underlying collateral first and foremost. We first find what we would pay by taking the "quick sale" value of the collateral, subtracting off the time value of money for a foreclosure, foreclosure costs, back taxes and tax prorations on the property sale, servicing costs, closing costs on the sale, and a spread for profit. We also price based on the yield we would need to hit if the buyer paid the loan as agreed. We then bid the lesser of those amounts. It is both science and art, but it is critical to your success.
I'm only really scratching the surface. It took me over 20 years of lending and collecting with some of the country's largest institutions to get where I am. Think about getting a strong, knowledgable partner. Good luck! I wish you much success.