Whichever side has the most fabric is face down on the feed dogs. The feed dogs help ease that extra fabric to fit the border or the quilt depending on which part has the extra fabric. Pin that extra fabric side to evenly distribute along the shorter side. Hope this makes sense.

I really don't agree with this. If that were true, pieces of the exact same length would now end up with the bottom a little shorter. Can you see what I mean?
If I were really concerned about this, I would pin at every intersection, as some do always. If there are no seams on one piece, I would mark the halves, quarters and eighths and pin them well.
It is important to have the two side borders the same length and ease in what is needed. Then the top and bottom borders also need to be the same length, too.

As you can see - Many different quilters and many different opinions here. So, you need to find what works for you - it is all good!! I am like Iceblossom. I am a pinner. Border on top and leading seams pinned. But I always press to the Border/Sashing so if there are seams to be nested - they get pinned as well. I have a Pfaff and it has it's own built in walking foot so I use that all the time. But if I am piecing on one of my machines without the walking foot, I stop every now with the needle down and adjust the bulk as I go.

Good advice. Thanks.

I, too, pin, but I have also found that if I put a small piece of tape along the front edge of my machine (just in front of the feed dogs but not covering them, a ramp) there is less chance of the seam trying to flip.

pay attention to the stretch possibilities
 

I entered a queen size quilt i had made for my daughter in last year's State Fair. I got a third place ribbon for it however one of the judges comments had to do with the border having stretched as i put it on. It was not intended for show when i made it, i didn't think i was good enough to warrant that. Apparently, ,my face when i saw the ribbon was a sight to behold.

This is also how I do it!

So many different schools of thought and reasons why one way or another! Thank you all for the feedback. I ended up putting the long border strip on the bottom and pinning the heck out of it. Worked more quickly and steadily once I actually got sewing. And, no, I didn’t sew over any pins. Too risky! 😁