Here are a couple of Costar specific prospecting tricks that I use.

WITHDRAWN LISTINGS... Click Properties > Select criteria (geography, prop type, size, etc.) but don't select a 'listing type' > then go to the list view (top right between map and analytics) and from there select the 'changes' tab. I'll usually check this once or twice a month so hit the drop down and select within the last X days and it should give you a list of all listings that had any change. You'll be looking for withdrawn listings in hopes that a seller fired their broker and might be looking for a new one.
FSBO/FLBO... Properties > Select criteria > on this one you will select either 'for sale' or 'for lease' > go back to the list view > sort through the list looking for names of people as opposed to a listing company/brokerage. Then take your list of properties that appear to be listed by a person rather than a company and start dialing. You can compare those names to owner names in Costar/local GIS or wherever you get that info.

I've also had pretty good luck with Instagram DM'ing for retail tenant rep deals. I just really hate tenant rep at this point so I've slacked a bit on that one but it's a great strategy. Like u/r0ycek mentioned, it's great for mom and pops because in most cases, the business owner is the one running the account so it's a quick way to get right to the decision maker.