Strategies on pulling equity out of current homes

I have a primary and a rental. I began a HELOC loan process to use funds to help pay for a new rental, but lost the property I was intending to buy with it, but it raises a question for me: If I continue to get the HELOC and it resides there ($150K unused), I assume this will greatly impact my ability to get more traditional financing in the future should I go that route.

I am trying to understand how you folks are able to use existing home equity to buy more properties that don't show income NOW, thereby pushing your income/debt ratio higher than banks allow. IN short, how are you able to use equity to do this?   When i read the posts in here they make it sound easy, but my banks say no.   They wont count "future income" as it doesn't exist yet.