I am closing on my 3rd single family in 3 days and would like to break in to multi family, but don't know how to evaluate the pro formas.

You can get a good deal on something that needs a little work, and hopefully have it up to "coasting speed" while you can actively manage the work.I would also form a trust and get an attorney/firm who is familiar with this type of situation to act as trustee upon your passing. 

You're asking about the income approach plus a lot of other questions mixed in too about actual versus pro forma. 

Here are some important tips you can use when first starting out in Airbnb to set up your business the right way:Legal EntityIf you just want to do this as a hobby which is just fine if you do then you probably don't need to form a legal entity.

You then have to decide what you reflect in Pro Forma if you do them.  

This means learning the language and metrics of CRE and how to use them to run pro forma analysis.Everything else involved with the investment or development process depends on the ability to define and underwrite the highest and best use of a property.If you do work with a mentor, make sure that they are coming from a place of real world experience and success especially in terms of meeting your defined needs and goals.In addition to whatever else you might bring to your mentorship, be prepared to be on time, provide questions and answers and be an active participant.

Many other sponsors only provide a pro forma with no sources/uses of funds, no detailed financials, etc. 

Note the 50% rule is not a substitute for a good pro forma estimate.Good luck

It does no good to place capital with a sponsor who has a project with an attractive pro forma to find out later they can't be trusted.

However, there are also some (much fewer) lenders that can finance STR acquisitions based upon pro-forma STR rent analysis.