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Accuracy accuracy accuracy. Do it slow and do it correctly and above all else, accurately. Do NOT buy measuring tools from ebay. Do not waste time on apps, phones are NOT calibrated measuing equipment.
For my CGEM-DX I used a plumb bob and accurate timepiece to line out N-S line at solar noon. Confirmable/repeatable over several days. No approximate markings or eyeballing or dodgy compasses used or needed. Masking tape, fine point sharpie, fine line string and weight and old camera tripod to dangle it from.
My celestron tripod allowed me to lock one side set of adjustment knobs leaving the other side free to fix with. This meant I could put the mount on top and get it N-S aligned accurately and permanently lock off one set of adjusters, using the other set to hold the mount in place. This allowed me to take the mount on and off repeatedly in the dark and it would be NS aligned. My ground was paved and likewise I used a masonry drill bit to drill three small pits the points of the tripod feet would seat themselves in comfortably. I was able to borrow a calibrated digital level to set the mount dovetail to my latitude as best as I could. With everything set up I was then able to put a piece of masking tape across the rotating joins, draw a fine black line across and cut with the join gap using a razor. This gave me parking marks to put the mount in for my "home" position and it would be pointing at SCP. at night i would periodically set up with just a dovetail mounted camera and take test long exposure shots. It was always obvious the camera at this "home" position was showing the SCP close to center of frame for my needs just above my roofline.
This process didn't take too long to work out, a couple of days to ensure I had a good NS line drawn on the ground and up the wall, confirmed over several days at solar noon. Then later when it was in place I could use a strong torch and plumb line rigged in my yard to cast a shade along the marked line and use that to help align and center my tripod etc. I later used a wax crayon to go over the line so it would be there for future use and wouldn't wash away.
It took me a bunch of nights to drag everything out and take a long untracked exposure to ensure scp was in middle of my camera sensor and Then I felt I could trust my routine was repeatedably alignable. And every few months I would double check when I was gearing up for a season target.
From there the only thing I had to worry about was balancing. I found it best to put all the gear on and slew it to where my target was going to be for imaging and then balance it carefully at that point. I could do my multistar alignment for the goto, btw this is all with just the mounts goto handset, no guiding camera or laptop control. The star alignment would look off as the rig would be slightly off balance pointed at anything other than my target. But once the alignment process was complete and I slewed to my target it would be dead center and stay there without drifting for the shooting time I needed at least.
Another gotcha though is the handset itself, first dont pull it far from the scope as it may be putting tension against the mount motors which can reduce alignment and tracking accuracy. Make sure the cable is very slack and wont catch on anything as the mount moves during the imaging session. Secondly is when you use the arrow keys to slew to a target often two of the direction keys will hold position when you release them while the opposite direction keys may contune to slew and even drift. I think this is due to the meshing tolerance of the gears themselves but not certain. Its easy to see when slewing to a planet or the moon. Test getting a target in center of view where your final button press/release is say the up arrow. Watch for the drift, repeat with the down arrow as the final press and watch for drift again. Sometimes there is a little extra slewing that comes to a stop and remains steady. Just observe what your gear does. repeat for left and right arrows too. I don't know if it changes depending on where the scope is pointing so it might change? Its something I keep in mind anyway and test quickly each time I image where I may need to manually adjust with the handset. Its very little bother to just check when setting up before imaging, especially shorter planetary sessions.
I know a few of these were touched on by others, but maybe some of what I've outlined can help too.
Accuracy and lots of patience and do testing too, I find all this is needed . Take your time, plan your goals for the session, eg testing settings only. and stick to the plan. Don't get distracted by that bright object over there and not get what you need to achieve your goal for the night, take note of it to make it your goal the following night instead. Especially when learning and trying new gear its easy to get distracted and sidetracked with other targets.
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