I avoid flying in a straight line. For example, if going from DTW-LAS, I'd connect via IAH or even EWR or IAD (if the fare remains the same). Use the multi-city feature to build a circuitous route. I did LAS-SFO-IAD-MCO and returned the next day.

500-mile minimums. DTW-ORD 233 actual miles but 500 PQM. I think only Premier Silver and above get this now. Non-elites get actual miles flown.

Tues and Weds (sometimes Thurs and Sat) generally have the best fares. UA seems to post sales on Tues.

Check out websites and podcasts. I don't think I'm allowed to mention the actual names but you may come across a "watchdog" site for bargain fares as well as podcasts that discuss "hoarding points," upgrades or "what's going on in travel this week."

Have fun. See you in the skies.