Is there any do's and don't to applying adhesive? Any trowling techniques that you could share. Any input is appreciated.

Important to keep the trowell as close to 90 degrees as possible , to get the full depth of the teeth.
Don't angle back past 90....the back of your hand & trowell handle will be in the glue .

Thanks, Floorologist. Is it a matter of preference as to how the trowel lines are to be patterned on the concrete? I've seen some photos where they fan the trowel 45 degrees; others form straight parallel lines in a row.

Some guys will say they trowell straight lines perpendicular to the wood for better bonding . IMO that's hogwash . They're either more comfortable trowelling that way, physically, or their used to trowelling that way for ceramic tile or stone products, ( Your suppose to trowell straight lines for these products to let trapped air release underneath the product ).
I have been trowelling in "fans" for many years.
The bottom line for hardwood is to use the correct size teeth, spread with the trowell at the correct angle, and have correct transfer of adhesive on the back side of the wood, AND roll the floor , ( which most guys don't do ).

I believe most manufactures suggest you trowel at a 45 for the correct amount of adhesive and the trowels are designed to give you that amount at that degree of tilt. Holding at a 90 degree would hurt and is not condusive to spreading easily.

Is that why my wrists are like iron, and I dont get the spread rate?! I can tell you this much... the woods down to stay

Ya, I believe Tucson is right. Seems I read that somewhere way back when and was relieved to find that I had been doing it correctly. It is SO much easier to spread at a 45 degree that I made the assumption that was the way it should be done.

Nothing wrong with some extra adhesive I guess. Of course your supposed to check for coverage every once in awhile. But if I needed more glue I would switch to a larger metering device. Before all this Stauf technique where your laying down tow layers of adhesive at once, all the adhesive manufcatures said not to use it for filling low spots, not it's like a lake anyhow.

I went to the Mirage website. They suggest trowelling at a 45 degree angle.

In the early 70's you were told as close to 90 as possible , that if you spread too low of an angle it would result in lower ridges. When I think about that, it makes sense to me. The top of the notch is lower to the substrate. Probably since that time they accomadated the lower angle with a deeper notch? Plus back with the LP adhesives it would be tough to spread at a 45 and push the adhesive ,keeping flat on the substrate, resulting in skimming or floating. I run into batches of adhesive now that good luck spreading at a 45. You have to put your body behind it.
Bottom line is , the way I look at it, I feel more comfortable with the transfer.

ya Floorologist, you remember that old LP mastic? Sheesh, after a couple of years of spreading that, there wasnt a guy at the legion who would dare challenge me to an arm-wrestling match. Nowadays, my grandaughters can beat me, lol.

45 degrees here.

A little tip on your trowel that I read a few years back in Hardwood Floors Magazine....I think.
Cover the bottom side of your trowel with tape except where the teeth are. It cuts a lot of time cleaning it at the end of the day. Just peel it off and clean the teeth. I use blue painters tape....it peels off easier.