The general rule is that a veteran may have only one outstanding VA loan at a time.   

If I am buying and holding, why don't I just find a good realtor who can find properties that need some improvement and rent them out?

You'll either want to create a partnership agreement or form an LLC and create an operating agreement, which will incapsulate both of your rules, responsibilities, rights and terms of the agreement.

These are not particularly onerous, and, quite frankly, are probably a good rule of thumb to follow.  

Also I even see clear improvement of neighborhoods which used to be bad.

In my opinion investors need to have a good understanding on maintenance and repair issues, as well as what it takes to handle improvements. 

PROACTIVELY Structure the deal.HOLD the property, refi and take out cash repeatedly if you need it and current lending rules allow ( that option cycles about every 5 years!)

You do this so that it lowers your monthly payments and allows you to improve cash flow on the property.

Within 12 months, I improved my credit score, got approved for a VA loan, and bought my first duplex!

Keep in mind local rules apply.