I fall into this category unfortunately
One of the best advices I ever got regarding photography was given to me by a journalist in Edinburgh, and I've been sticking to it 95% of the time since* :
Manual mode : F5.6 - 1/500 ; and work from there. (as well as being locked to 200iso, and shooting in raw, but if you have an SLR, you should already be doing that)
Play with the speed dial first, down to 1/90, after that shutter speed is too slow to shoot handheld.
If you still need a bit more light, open the aperture a bit more (but try to avoid going to the lowest value possible if you want a sharp picture), or try to find a support to stabilize your camera.
If that doesn't cut it, there is no secret : you either need a tripod or a flash (depending on what you are shooting), because what the camera would do next if it was in an auto/semi-auto mode would be to jack up the iso, resulting in a noisy picture (well again, it depends on what you are shooting and for what purpose, if you are not planning on getting large, high quality prints, it's not that important).
*the rest of the time, it means that I have less that 1 or 2 seconds to make the shot, with no time for prep ; so I actually do switch to full auto, but knowing that I will most likely end up not using the picture.
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