Furnished Finder means you will need to have more interaction points to process them and collect payment--- does not mean it's a bad option, but there is less automation involved.

Go to Etsy and search for "rental property tracker," and you will find hundreds of nice spreadsheets to track 10-20 rentals, usually for under $10.Software has extremely helpful features like online payments, marketing syndication (click a button, and your property is advertised on multiple sites), electronic document review/signing, maintenance tracking, and owner reports.

Again, the BiggerPockets store has some books on this topic, or you can learn about it by watching podcasts, reading blogs, and interacting on the forum.

Hey @Tarcizio Goncalves, QuickBooks Online allows for everything you need. 

The successful wholesalers I know spend $8,000 + per month on online marketing, SEO, SEM, landing pages, lead conversion, etc.  

For building a buyers list, I’d recommend joining local real estate investment groups, both in person and online.

Lots of material online.  

Also, access to online HMLs is compressing the total returns as the market gets more efficient.

@Greg Soon I work in QuickBooks online with only Real Estate Investors. :) 

Welcome to the BP online community.