I recently got a new macro lens and after a couple of outings I noticed it would be very beneficial to use monopod or a tripod (or some kind of support). I would prefer a monopod because it seems more portable, but a tripod has a lot more support. I typically go on photo walks for most of my pictures (I can only take so many pictures of my place), so portability is a big seller. Has anyone had a lot of success using a monopod for macro photography? Or should I suck it up and lug around a tripod?
First we need to understand if you're actually shooting at "macro" focusing distances, or just "close-up."
Life-size is the typical aim of "full macro" shots, which is to say you are working at a 1:1 reproduction ratio, shooting very small objects at close range. Insects, flower stamens, etc. There are two problems typically encountered here that are tightly related: thin depth of field, and camera movement. You're working in such a small area that the slightest movement completely changes your composition, and depth of field is so slim that even with the smallest apertures you're fighting to get everything in focus. You're also fighting to get the camera's shadow out of the frame, and traditional camera-mounted flash is useless because it shoots above your subject since the camera is so close. Because you're fighting DOF you are often shooting smaller apertures and creating longer exposures, too. A tripod is basically a necessity if you're working on still subjects, and a focusing rail may also be useful/required. For moving subjects... well, just find a composition you like, and wait for the subject to come to you. Tracking a frame-filling bee, for example, is basically impossible.
Close-ups are what most people mean when they say "macro." Your subject is typically small -- a model train, perhaps -- and you are working at relatively close range. The process for shooting is very much like any other shot, though, where you just need to have good technique to get the photo you want. Your camera-mounted flash may even be enough to reasonably light the subject. You can typically use the support you prefer or require based upon shutter speeds.
Monopods have their place, but realize that their absolute stability is definitely less than a tripod can offer. While a monopod may help you get better shots, I'm sure a tripod would, too, and will let you get shots the monopod would not. If you've been taking photos that are just not quite sharp enough, then a monopod is probably a fine choice; otherwise I would recommend a tripod.
This highly depends on what you are shooting. For example if you are shooting insects then you will need to get a tripod cause you don't want to wake up the sleeping bee by you trying to adjust the monopod. However if you are shooting still objects (flowers, coins, ...) you can go for monopod. The problem with monopods is that you are involved, if this is okay with what you are shooting then use monopod.
Another technique for stabilization is to use something like a bean pole. Hold on to the pole with your hand that is also holding your camera. This gives similar stability to a monopod, but allows you to easily adjust the height.
If you're looking for maximum stability along with maximum portability, look into the Canon 100/2.8L macro, which offers a better IS for macro. See this thread: How useful is image stabilization in a macro lens?