Give some details about the house you are looking to deal with. If there is not a specific deal, then make up a realistic scenario that would encompass your dream deal. Realistic does not mean the mint condition Ferrari that was found in the barn....it means a deal that is good enough to make it worth your while but not so great that 35 other investors would either find it first or pay more than you.
How much capital do you have right now? This could be cash in the bank (preferably) or other capital you could easily, quickly and cheaply access (not a HML or traditional loan).
For me...in my area....the ideal house has ARV between $70,000 and $150,000. I am a buy and hold investor. I don't flip. When I buy the house, the most I would be willing to have invested in the deal was 80% ARV and that is if it is in a great location etc. 80% is absolute max for the best of the best. If the house I was looking at had an ARV of $100,000, I would immediately subtract 20% or $20,000 since I invest a max of 80% ARV. Then if it needed $20,000 of work you would subtract $23,000 for work ($20,000 planned + 15% contingency), $4,0000 for closing costs, (1 time to buy and 1 time to refi in 6 months) and subtract the cost of capital prior to refi....lets assume $60,000 HML @ 15% with 3 points. That would be an additional $1800 in points + $4500 in total monthly interest payments for 6 months). In this simplistic example, that would mean I would pay no more than and preferably way less than ($100,000 - $20,000 - $23,000 - $4,000 - $6,300) = $46,7000.
So, with this scenario, you would get it under contract for no more than $46,700, borrow $60,000, leaving you with $13,300 to make $20,000 worth of improvements, cover contingencies etc before you can get it rented.
Once the work has been completed and you have owned it for at least 6 months, you can go get a cash out refi at 75% ltv. So, $75,000 - $60,000 gets rid of the hard money loan and puts $15,000 back in your pocket. The refi lender will want to see reserves to pay insurance and taxes for a year and at least 6 months worth of payments. That should not be hard. Just make sure your DTI and credit score are good. The numbers are simplified somewhat because I showed paying the refi costs and HML points and interest payments earlier in the subtracted values to determine max price to pay. In reality, you pay those amounts at different times in the process but still want to account for them in your calculations.
I am fortunate in that I have better alternatives than HML's so there are likely some details I left out since I have not ever dealt with one. But this should be enough to get you going and whatever HML you decide to work with can fill in the blanks or make corrections as needed. You might even want to find a small local bank that does construction loans. Better rates and options to convert to permanent financing but requires slightly better qualifications than a HML. Depending on how aggressive you want to get, how much debt you currently carry etc, there are options with 0% cash advances on credit cards (maybe an existing card or just open a new one and cash advance to yourself). You could refi your car to get extra cash, borrow against 401k or simply hit up someone you know that is willing to risk some money on you in return for above average interest. A HML is the last resort for me and so far I have been able to avoid them. They are certainly of value, but way too expensive for me.
Good luck.