When lending ~15k to rehabber short-term, what to look out for?

[George P.]

I have been (briefly) pitched by a rehabber who needs $$ to rehab multi-units, occupy and resell 18-24 months later. Promises 8% and percent of profit upon closing. Claims it'll be secured by 1st lien (I have to mention that these are lower but not lowest end properties).
Since it will (if I decide to pursue after doing DD) my first lending venture, what should I look for?
Thank you in advance!!

PS I have a traditional Roth, and currently decide between the custodians and facilitators for SD IRA.