Get rid of debt, build a budget, and save.

one furnace would take up 4 years of your capex budget.

From there, you ask more detailed questions, like will you provide budget versus actuals on current projects?  

Make sure you set aside a monthly budget for maintenance and have the proper insurance in place for maximum protection.I would suggest starting with a single family unit before multi-family as you get used to the business. 

Key determinants include the percentage of owner-occupied units, contribution percentage for the HOA budget towards reserves, and a clean record without litigation, delinquencies, or major issues.

It is easy to underestimate your rehab budget. - make sure to get bids from multiple contractors.It is easy to overestimate your ARV. - Have an agent pull recent comps for youIt is easy to underestimate the timeline. - whatever a contractor says, add 4 weeks.

To help with you issue of cash flow, consider the idea of financing your rehab budget with your hard money lender.

They should say, no, I will do it for you in hopes to get business.I think that a good GC with decades of experience should charge, say $200-$300 for 1) a review of the Inspector's report, 2) a jobsite visit, plus 3) a budget with prices that are pretty close.

Ultimately, the best choice depends on your preferences, budget, and maintenance preferences.

Contractors don't usually like working with them because they are so tight, budget-wise......