"Make certain that the secondary mirror is centered directly under the focusser. The cross-hairs of the Cheshire can help with that..."
The spider (secondary mount) does not have to be "exactly" centered in the telescope tube. A good attempt to measure and put it as close to center as you dare is good enough. We're not after "perfect" mechanical alignment, just good enough to make precise "optical" alignment easier.
Try this after getting a nice looking centered secondary under the focuser as Sky Muse shows a few posts above. Remove the paper blocking the secondary. You likely need to (or should) check and refine your secondary rotation before you start tilting the secondary. It may be good enough, maybe not.
It can be difficult to eyeball how circular the secondary appears to be under the focuser. When you remove the paper, the primary reflection might be seen almost anywhere in the secondary. The closer it is to the secondary center, the easier collimation will be.
Just because the secondary looks circular doesn't mean it's pointing or sufficiently rotated relative to the primary and the center marker. For that, you might want to actually see the primary reflection because accurate axial alignment is more important than a circular secondary placement. Good refinement of your secondary rotation will save some effort during secondary axial tilt.
If the primary reflection is off the secondary center line, loosen one of the secondary adjustment screws (in-line with the focuser) so the secondary can rotate freely enough. Not sloppy loose, leave some light friction to hold it. Rotate the secondary so the primary reflection is centered on the secondary's major axis. The horizontal cross hair can help guide you as shown in Sky Muse's image, then tighten that screw. Don't worry about centering on the minor axis, tilt will take care of that later.
Now you're *more* ready to tilt the secondary and align the focuser axis with the primary center. Doing so will bring the primary toward center of the secondary pretty much (mostly) along the horizontal cross hair until the primary center hits the (vertical) cross hair. You will save a little confusion and avoid potential difficulty during collimation.
"As a newbie, I’ve read 5 different methods and some contradict each other. I’ll work with Cheshire exclusively. That seems to give me the best results."
Yes, the site tube/Cheshire will better help center the secondary. And yea, many of us have developed techniques to do the exact same tried and true collimation steps. We develop slightly different methods to skin the same cat, to do the same steps and arrive at the same place. I offer mine if you understand and care to try it. Saved me a lot of additional posts on CN.
Edited by Asbytec, 14 August 2020 - 07:20 PM.