A Kodak book on shooting with available light had advice on developing a steady hand. They suggested that you tape a mirror to your camera aimed a few degrees to the side. Set up a point light source (a flashlight was suggested) in a dimly lit room, and stand, aiming your camera at the light. The spot of light that is reflected onto a nearby wall will show your hand movements, greatly magnified. Practice holding steady until the light doesn't move.
Don't know if it would work for you, but it's cheaper than simply shooting until you get sharp images.
Quit drinking whiskey, quit drinking coffee, quit smoking, get enough sleep. Try holding your breath while pressing the shutter release, all come to mind.
When all this fails, then get the tripod. Then you can take up the bad habits again.
Cut down on American coffee (ground variety). This weekend past, I went to a village scarecrow competition close to where I live. People had built amazing scarecrows outside their houses.Great photo opportunities. The whole village was a kind of "open house" and at one house a genuine Texas lady was serving genuine Texas coffee. Very nice but very strong. I was super alert after one cup, would have defended the Alamo after two and chased the Mexicans back across the Rio Grande after three and been banned from competing in the Tour de France for life!
If I drank as much coffee as I do tea and I don't do that excessively, I'd be seriously "twitchy".
As you aim the camera and breathe, between the heartbeat, the breathing and the natural rhythm of the body swaying, there will be a limit cycle. This is a circular or elliptical pattern that the camera lens will repeatedly swings through. Hold your breathe or let it out, whatever works best for you, and pick the time when the movement in the limit cycle is minimum - that is when to shoot.