Most great sponsors do not have podcasts or similar digital presences (that doesn't mean the ones who do aren't legitimate). The best sponsors are focused on running their real estate deals. It's an intense business. You want your sponsor operating real estate and finding good deals--that's a 60- to 80-hour per week job.
First, you should be comfortable doing due-diligence on the deals and verifying the sponsor's assumptions in the model. For some context: in deals with sophisticated LPs, sponsors will send their model and the LP will then pick apart that model. LPs often underwrite the deal with their own model.
Underwriting takes practice. If you can, ask for trailing-12 expenses from a current property they own so you can verify that their model's projected operating expenses are in line with their current market operations. Sponsors are in the business of doing deals and they need those deals to look attractive to investors so they can get their fees. Thus, assumptions may get a little ambitious-- but that's for you, the LP, to determine. Some sponsors are conservative, some are aggressive.
Second, in respect to the sponsor as an individual or as a team of individuals, you want to see a track record of successful deals--and preferably successful exits. If they've just started but have 2-3 deals under their belt in the past year, it's too early to know if those deals are making money or will make money in the future. That's not to say you shouldn't invest with new sponsors, but it does mean that you need to spend more time diligence-ing the deal with your own assumptions and market research. Further, you need references--including character references--for newer sponsors.
Finally, and I've mentioned this in other posts, you want to make sure the sponsor has incentive to work hard to achieve outsize returns, but you don't want them taking too much of the deal. So, if a sponsor sends you a deal in which you're projecting an 18% IRR over 5 years to yourself, the sponsor shouldn't be receiving 50% of the total cash flows from that deal--that would be well-above market. You want a structure in which they're receiving 20-30% of the profits when you hit your 18% hurdle (as an engineer, you'll get this math relatively quickly). Structures in which the sponsor receives more than those percentages are often imbalanced and result in the sponsor making a lot of money even if the deal doesn't meet your return thresholds.
Understanding the fee structure dovetails with this: Sponsors can't be "feeing up the deal" so they get all their capital back before a check is delivered to the LPs. You also want the GP to have skin in the game until you get your initial invested capital back.
Regarding your returns: an 18% IRR over a 5-year hold period is not unreasonable but will take skill to achieve. It's a competitive market and sponsors can only achieve returns like that through heavy value-add programs. Make sure the construction budget reflects this. And if they're using bridge financing, make sure the deal isn't too risky because those are the first deals to go underwater when a market corrects.