So I was shooting a wedding last weekend and number of issues came up that are worth mentioning and what I did for each of those situations. To set the scene, it was supposed to be a fully outdoor wedding in a large open space which really is a dream come true for the photographer - loads of room to move around in, reportage-style, candids etc would have worked amazingly for the whole shoot. However, by 4pm the heavens opened and everyone ended up indoors in a narrow converted barn which posed a few photographic challenges...
This is the photographer's worst enemy as it can not only ruin your equipment but can also spoil the shots. First you can get water on the lens and this needs to be moved post production in PS etc. But worse for the wedding party/guests, their outfits/mood/patience etc can be hampered and it makes the shots difficult to create.
I always have an umbrella in the car. An assistant sometimes helps with this although I can wedge it into my backpack and it keeps me and the camera dry (plastic bags and elastic bands help with this too). Use your lens hood which may stop a few drops hitting the lens. Always point the camera down when not using it. Use the cap in between shots. Do the portraits etc quickly and slickly (but at the same time try not to look rushed). Have your shot program to hand to facilitate the speed of the shots. Finally you might have to accept that things need to be moved in doors so have a backup shot plan if that happens.
Problem: Poor Indoor Lighting
This is always an issue so you have to be aware of your camera's limitations and what you can do to get the most out of it and what you can and can't fix in post production. High ISO, large apertures and slow shutter speeds all generate further problems.
TRIPOD!!! This is a must. It keeps everything steady and reduces shake at slower shutter speeds. I also use a remote to activate the camera without having to touch it. I try never to go about ISO 1600 as I know that the noise the camera generates above this becomes difficult to remove in post production. Large apertures are worth trying but can cause "soft" images and aren't as sharp wide open so try not to open them fully and accept that the shutter speed has to be slower to counter this - which may result in blurry pictures from moving/animated subjects. To get around this pay close attention to your subject and wait till you think they are about to hold still then fire off a burst of shots. It's not an exact science but you should get one or two usable images each time.
Using a Flash Gun is also worth thinking about. However, don't buy today and shoot tomorrow (as with all equipment) as you'll just get frustrated when you realise you don't how to work it. I personally hate flash images but I reckon that's because I'm not very good at them. I do have one setting that works well...
35mm (prime) at 1/60th sec f4 and ISO 400 with 1/8th power on the flash. Seems to give good shots each time. But remember to "bounce" the flash off a white wall or ceiling or use a diffuser to try and stop harsh shadows. Also a tripod is not really possible as you need to be mobile so remember to "tripod" yourself on a wall or knee to steady the shot.
Problem : Distance to Subject
Sometimes you can end up so far from the people you are photographing that you have to be quite inventive to get anything worth using. At one point at this wedding I was about 40ft from the top table and there was no way to get closer due to the other tables. Being so far away requires long focal lengths and the amount of shake is mental. The distance is not the only problem here but also the lighting because you can't use flash beyond certain distances.
See my points about having a tripod and then scrap the one you were going to buy and buy the best one you can afford. It's probably going to last longer than any other bit of kit you have so it's worth investing. I shot quite a few pics at 200mm and it took a good few seconds for the shake/vibrations to settle down each time I moved the camera. Also bear in mind that loud speakers/amplifiers will cause vibrations and shake will take place in your pictures so try to take your shots in between rounds of applause etc. Again use a remote.
Also scout the location in advance so you at least have an idea about where you will and won't be able to get to with the camera. If needs be, get set up way before the speeches and wait it out until they start so you can get the interesting shots.
On this particular occasion I shot most of the speeches at 150-200mm with ISO 800-1600 and 1/40 - 1/30th and just had to accept the limitations of the equipment and resort to post production "fixes" which, although not ideal, seemed to work out OK. Beware again how noise reduction software can make your pictures "soft" and they lose sharpness.
Anyway, I hope that's useful. It's certainly worth considering all of this in advance of an important shoot as you often only get one chance to get the "must have" shots.