I haven't done a full remote BRRR but here's a few pointers I learned from lighter projects:
1. Payment structure: Regardless if it is local or remote, you’d want to structure payment to specific milestones in the payment terms with timelines in the contract. It's hard to say what % because it depends on what needs to be done. For repairs like roofing, siding, decks, etc expect that they will want more $ upfront because of materials which would be different than repairs that are more labor intensive and can be paired against rough/final inspection milestones.
2. Contracts and Addendums: Always document, document, document via a contract and you should try to itemize as much as possible and include any warranties in writing. If the scope changes, address it in a Change Order along with the additional scope, fees, timelines for completion and payment terms. The original contract should also note that "any changes affecting the cost of the job must be priced in writing and signed by both parties before work commences."
3. Comprehensive work: Try to tell them itemize as much as possible but include an overarching disclaimer in each repair section, something to the effect of: "Materials and labor provided by contractor unless otherwise specifically excluded in this section, to be provided by homeowner." Also include in the end somewhere that it includes all dumping/disposal fees unless that's something you specifically didn't want to include. Learned the hard way one time when they told me after I signed that I needed to call for a dumpster.
4. Keeping on Schedule: I haven’t found a foolproof way to motivate a contractor besides holding back a sizable installment for them to finish the job. I have read in the David Greene book that you could offer them a bonus incentive if they finish early?
5. Checking Their Work: Mostly, I have asked my property manager to check the contractor’s work and to send me pictures and/or facetime since they would have to deal with the property going forward and they're there to pick up the keys. In specific instances, I have had my agent drop by to check in as well.
Hope some of this helps!