I hadn't planned on using switch machines under a couple of turnouts, and change my mind after they'd been installed. But I was able to drill the actuating wire hole from underneath. Just be sure to measure the total thickness of your subroadbed and roadbed and use masking tape (as above) to mark how deep to drill so you don't demolish the turnout.
Another one from Bill... Want to temporarily hold track in place but are using foam subroadbed? Can't use track nails or spikes - so use a drywall screw instead! Note the screw head in between the closure rails on this turnout. Holds things nice and secure while you're futzing around with track arrangement or waiting for the glue to dry.
Mike Confalone suggests removing every 6th tie and respacing to suggest secondary track. I tried it for a section of the mainline between Essex and Deep River, but I'm not sure - yet - whether it's worth the trouble. Be careful if you do this with Micro-Engineering track. It'll make the so-called "flex"track more flexy; but the downside is it also makes it a little less stable and more fussy to handle. So be careful if you try this. I'll likely do this for my sidings, but maybe not for any more of my main. We'll see.
Beware - ACC burns through foam
Don't check track gauge when the power is on. ZAP!
Micro-Engineering rail joiners have a reputation for being difficult to use. I took a short piece of rail, filed the corners and chamfered the ends to make this handy "rail joiner spreader & installation" tool. Slide the joiner on, wiggle it a bit to loosen it, and then use the rail/tool to install the joiner on the end of the track. MUCH easier.
One of the most common causes of poor ops (read: derailments) is having kinks in your track - especially on curves. Your eye is the best tool for eliminating kinks, but all-too-often you can't get your eyes where you need them. So take a mirror and sight along the line. Got this tip from a Joe Fugate video and have used it often since.
Hope you find something useful among these quick tips - and if you have a tip of your own to share that you've found particularly helpful, put it in the comments!