Updated: Sep 12, 2019
One thing I can't stress enough is learning your tech before heading out into the field. On several occasions I have made the rookie mistake of simply heading out to a shoot after having only opened the box and powered on a piece of equipment. It is incredibly embarrassing having to bust out the owner's manual to figure out why a piece of tech isn't working while the client stands watching with their cold, judging eyes.
Okay, maybe it isn't that bad, but it is unprofessional. On one occasion after I first bought my Zhiyun Crane 2 for my Canon 5D Mk iv, I spent several hours learning how to balance it, but little time practicing using it. I was on a shoot and kept losing shots because the gimbal would suddenly jump to the right when making a pan. I lost a lot of time and endured much frustration because I was unfamiliar with the tool. Later I learned that by holding the handle in a more vertical position it didn't jump when panning, but had I spent a few hours practicing I would have been more familiar with the move.
I had a similar situation with my Tascam field recorder. I had a client all mic'd up and standing in the hot Arizona sun while I read the instruction manual to figure out why I was only getting one channel of sound. Very, very embarrassing. Fortunately the client had a great sense of humor and thought it was funny, but I was lucky. Could have lost a client and future business.
Of course there will always be malfunctions and surprises on every shoot, but the more familiar you are with your tech, the less surprises and halts to production there will be. Practice for several hours with every piece of tech, no matter how small it may seem. Besides, isn't it fun to play with your toys anyway?