The good ROIs I've seen are a combination of a handful of good factors. For the case where they went from sub-1% to above 2%, the series of events was:
1. Saw an MLS listing in one of my focus areas with 2 duplexes on one lot for $370k-ish and each unit at $800/mo
2. (Quickly) came to learn this was one of like 10 properties being sold by a trustee with a very mediocre pm. Made the case that this needed commercial funding and that would push down return (and price).
3. Got it under contract for $350k-ish and negotiated a long evaluation phase, so I could confirm the properties could be split in two.
3. Closed with short term owner financing
4. Refi'd into two 30-yr fixed 6 months later
5. Painted interiors (another $10k?) and upped rents to $1400/unit at turnover about a year after purchase
6. Having kitchens redone now on all four units plus some exterior improvements ($40k total) with projected rents at $1800/unit in the fall, with potential to nudge to $2000/unit year after.
These are very large - each unit is 4br/2ba - and ideally close to a college, so the key here was repositioning with students in mind.
To make sure my overall point wasn't lost in these details: no genius involved here, no hot market or abnormal appreciation, just simply having broad knowledge about a focus area and being known by agents/pm, makes unlocking things like this possible. There are no online links you will find that offer up quality 2%. You find them via phone conversations with a variety of people and assembling disjointed facts into a plan that optimizes for best opportunity.
That said, it's been 1 year exactly since the last good purchase, and I've been looking hard, making offers, etc. Hopeful 2019 isn't as difficult to find deals.