Short answer — use a mix of (A) alliance/airline searches, (B) aggregator/award‑search engines, and (C) alerts + phone calls. Below is a practical step‑by‑step workflow, the best tools to use, and tips to avoid common traps.

Workflow (step‑by‑step)

1. Decide dates / flexible window and whether you’ll accept one‑ways or mixed airlines. Searching one‑ways often reveals combos that round‑trip searches hide.
2. Search the major alliance/airline sites first (Star Alliance, Oneworld, SkyTeam and the big programs you can transfer to) to get a baseline of availability. If you’re using a program to book, start in that program’s search. Many airline sites show partner flights (but results can differ between sites). (princeoftravel.com)
3. Run an aggregator/award‑search engine to compare many programs at once — these save huge time and surface partner options you might miss. Use the aggregator results as leads, then confirm on the airline program you’ll actually use. (point.me)
4. If you find the seat on an airline’s site but not the program you want to use, call the mileage program you intend to book with (agents can often see/book partner space that doesn’t appear online). Also try logging out of your airline account when checking inventory (some sites show different “hidden” inventory when you’re logged in). (thepointsguy.com)
5. Don’t transfer transferable points until you’ve confirmed the award space is bookable in the program you will use. Once confirmed, transfer points (some transfers are instant, others take time). (forbes.com)
6. If you can’t find availability now, set alerts (ExpertFlyer, aggregator alert features) and keep checking — last‑minute and schedule‑open releases are common. (thepointsguy.com)

Best tools and what they do

• Airline / alliance sites — United, Aeroplan, British Airways, etc.: authoritative for that program and often the best calendar interfaces; but availability can vary by program. Use these to confirm and to actually ticket when possible. (princeoftravel.com)
• Point.me — paid aggregator that searches many loyalty programs and shows booking options and transfer routes; good for comparing many programs at once. (Has free tier + paid). (point.me)
• ExpertFlyer — good for detailed award inventory checks and for setting alerts; coverage varies by carrier but it’s useful for monitoring specific flights. (Paid.) (thepointsguy.com)
• AwardHacker / AwardFares / Roame / other aggregators — AwardHacker is useful to see which programs can book a route (static guidance); AwardFares, Roame and others offer live searches/alerts (coverage and accuracy vary). Use them as complements to paid aggregators. (awardhacker.com)

Practical search techniques

• Search one‑ways and build an itinerary from segments. That multiplies your options and allows mixing partners.
• Use nearby airports (both origin and destination) and alternate routings — partner airlines sometimes have space via unusual hubs.
• Use the alliance approach: find availability on any Star Alliance carrier if you have Aeroplan/United/LifeMiles points, etc.; same for Oneworld/SkyTeam. Then confirm which program offers the best price/taxes and which will actually ticket. (princeoftravel.com)
• If you see a seat on one airline’s site but not on the partner site, call the program you will use — agents can often ticket partner space or manually see inventory not displayed online. (princeoftravel.com)
• Set alerts for specific flights/routes. Many tools support alerting so you don’t have to manually re‑search daily. (thepointsguy.com)

Points/transferability rules (important)

• If you plan to transfer bank points (Amex, Chase, Citi, Capital One), confirm the target airline program and availability before transferring. Transfer times and ratios differ by partner; transferring before confirming can leave you stuck. (forbes.com)
• Watch carrier‑imposed surcharges and award taxes — some programs add big cash surcharges on certain carriers/routes (e.g., some BA/partner redemptions). Compare total cash outlays, not just miles. (cntraveler.com)

Common pitfalls and how to avoid them

• Aggregators aren’t perfect: they may miss inventory or show cached/partial results. Always confirm on the airline/program that will actually ticket. (wsj.com)
• Logged‑in inventory: if you have co‑branded cards or status, sites may show you extra inventory that partners can’t book. Log out to verify partner‑bookable fare codes (e.g., United “X” vs “XN”). (thepointsguy.com)
• Transferring points too early: transfer only after you’ve confirmed the award can be ticketed; transfers can be irreversible and sometimes take days.
• Expect phone fees/agent fees for complicated partner bookings — a small cost can be worth it for premium cabin awards.

Quick checklist before you hit “transfer” or “book”

• I’ve confirmed award seats for each flight segment in the program I’ll use (online or with an agent). (princeoftravel.com)
• I checked taxes/surcharges and phone/processing fees. (cntraveler.com)
• I verified transfer times/ratios for my credit‑card points. (forbes.com)
• I set alerts or put the route on a watchlist if no immediate availability. (thepointsguy.com)

If you want, I can:

• Give a prioritized list of tools for a specific route (example: U.S. → Europe in business) and explain which loyalty programs are the usual “sweet spots”; or
• Walk through a sample search for one route (showing which tools to use, in what order).

Which would you like me to do next?