Finding a good hard money lender is critical to success. I would ask other investor around your area about this lender and others.
How do they underwrite the property?
Do they require an appraisal or do they determine the value on their own? If they do it on their own I suggest you consider paying for an appraisal so you know what the ARV is likely to be. It is worth the money to get the valuation right. Then get that rehab done FAST. Otherwise the comps fall off or the world can change on you and you are stuck. Typically real estate values do not change quickly but one bad company can cause issues on a flip or refi.
Do they require draw inspections? How many and what do they cost? I do not mind paying for draw inspections. It gets a third party set of eyes on the property and helps keep contractors honest. You can do that on your own, but you need to do it. Is work progressing? Are the materials the same as agreed to in your scope of work and the signed contract? Are change orders documented and executed properly?
What documentation do they require for draw requests to pay your contractor and what is the delay time for payment? Or will you front the cost of rehab and get it back at the end? This is really important to know if your liquidity is low. You have to sync up your draw schedule with your contractors to your draw schedule requirements from your hard money lender.
Do they have a track record of closing on time and not backing out of deals ( some are undercapitalized and suddenly do not have the money to close).
What are the costs involved if you cannot sell or refi the property by the end of your hard money loan agreement? Will they provide an extension? What is the cost? How long will they extend? Some will extend for 1-6 months, some will increase the interest rate and/or charge an extension fee. Make sure you will not end up upside down if rehab is delayed ( city red tags can kill you)
Are there any backend costs? Some hard money lenders have low interest rates because they charge the rest on the back end. They consider it a plus but you have to calculate the full costs into your numbers up front.
Finally, if you are flipping. Don’t forget about holding costs:
Hard money interest and fees, yard maintenance, utilities, insurance (Make sure you have the right policy for rehab and an empty house - builders risk. If you get a regular policy and are cancelled the builders risk policy will be much higher mid rehab than at closing when you buy) and property taxes that are accruing, And cleaning if it sits for awhile while being marketed for sale or rent.
Good luck, hard money used wisely can increase your profit!