When using a DSLR or TV camera for video I would always heavily advise against using it “handheld”. This is because, to put it bluntly, it pretty much always looks terrible and unprofessional. The issue is that it introduces a lot of micro jitters to the footage (on top of regular jitters) due to your hands being naturally unstable. There are shoulder mounts available at the media store which work quite nicely, but if you insist on doing it without here are a few tips:
Try and have three points of contact on the camera. With a DSLR this can be tricky, but I think the best way to do this is to have hands on either side of the camera, and then have the neck strap as the third point pulled tight away from you.
Another option is weighing the camera down as much as you can. A big difference between going handheld on a big budget feature film using a cine camera and going handheld with a DSLR (aside from being operated by trained industry veterans) is that the cine camera is much bigger and weighs a lot more. Its that weight that cuts out those micro jitters leading to much smoother visuals. Weighing down a DSLR is tricky so the first tip is probably the more feasible option.
Using a wide focal length rather than a short one. This makes the camera shake much less noticeable as moving the camera zoomed in will make the image move further than it would zoomed out.
Finally, when moving the camera turn with you hips and stomach rather than your arms and hands, as it is a much stronger stance and it lets you focus your arms on keeping the camera still.
As previously mentioned, at the media store we also supply shoulder mounts which I would highly recommend instead of holding the camera in your hands. The shoulder mount uses your shoulder as a third point of contact (along with your two hands), which creates a much more stable platform than just your hands.