You'll want one for two reasons (you can decide if this is important to you)1) If you're emailing/mailing people or advertising online, you'll want to direct to your site where you can capture their data (name, address, etc.). 

For example, I have heard of people who wrap their cars to advertise brands.

I am a CA broker you can go to the DRE websites for the disclosure docs that are mandatory for CA.. many states though have a carve out for mom and pop lenders who are not advertising or holding out as lenders and do a few a year.like Oregon you can do 3 a year and no more than 7 in your portfolio.So check your state .. many states or should I say most states  all but 12  commercial purpose non owner occ loans are exempt.. 

@Lamar Robinson Wholesaling is advertised as a quick and easy way to make a bunch of money without having any of your own cash or credit.

I am curious to know the systems other experienced investors use and any tips or tricks that make a direct mail campaign successful.

Owner would list the property and have no clue that they were sitting on 500k worth of trees'  especially ones that would own in ORegon and advertise in CA.. thinking CA investor were not bright and would over pay for Oregon properties ( its a common notion in Oregon)..

We going to use a direct mail campaign such as "yellowletterscomplete.com."   

I currently work full time for a marketing agency, and specialize in search engine optimization, paid advertising, & analytics.

Another avenue you can pursue is canvassing Owner Finance notes, with a letter or SEO campaign, etc.  

Each color comes back from corporate at a different price point but we were able to find one at around a 30% discount from the in store advertised price.