My first project in the last 25 years was this around the ceiling layout, composed of a roughly 60+ foot run of track, plus a staging yard. Keeping a tight budget was a chief consideration. There are a few lessons learned here that I think are worth passing along to any other newbies.
First, one's first project in 25 years should NOT be something grandiose. Stay humble, learn small. Maybe start with a switching shelf (my second project; WAY more successful).
Second, build the shelf FIRST, lay track AFTER. Make sure it's level, and unless the space enjoys constant temperature and humidity, ensure the shelf material is both level and sealed (painted/poly'd), or is not something susceptible to atmospheric interferences (foam). (Mine's in a New England basement w/ a wood stove; hot and dry in the winter, cold and damp in the summer)
Third, used track isn't worth the trouble. The massive investment in time and energy in reconditioning used brass track isn't worth it, and the many separate pieces makes the total layout far more susceptible to kinks/bumps/etc. Buy new 36" flex track sections, and lay that onto cork, on top of the shelf.
Fourth, leave spacing between lengths of track. Insert a business card between ends when tacking down track. That will take care of thermal expansion issues. If two pieces of flex track will be joined to make a curve, solder them together when straight, and then bend them, with the soldered joint in the middle.
Fifth, for a ceiling layout, On30 is a fantastic option. It's O scale models of narrow gauge trains, running on HO gauge track. Bachmann makes the vast majority, and there are generic 2-6-0s readily available on the used market. Use search terms like "Hawthorne," "Bachmann," "Bachman," "Kinkade," "Bradford," to find some novelty collectible train sets that sell for short money used (see the 'Murica cars in the video's consist). Facebook Marketplace seems to the ultimate best for deals these days. The Bachmann On30 2-6-0 Mogul is actually a fine loco, with a frak-huge flywheel to help it keep momentum, which makes it highly tolerant of power interruptions. Plus, being physically larger than HO scale looks better when it's running around the ceiling.
Sixth, do the electrical right the first time. It's the one thing I did right from square one; 2 huge honking bus wires (12 gauge wire) feeding track joiners at every other junction. I've never had a power issue.
Lastly, the staging yard was a BAD idea. Don't do it. Instead, do long passing sidings, if you have a long run of track, you'll want to run long trains, and taking them down and putting up others is a pain. Space them for On30, not HO; On30 is awesome, and you'll want more.