Cables & Connectors
You might think there isn't much to say here, but you'd be surprised!
Length
Cables come in two types, fixed length (eg. 1m, 5m, 10m, 20m) and custom lengths. Fixed length is best unless you need something special like a snake.
Colour
Standard colour for most instrument and XLR/microphone cables is black. This is fine until you need to figure out which of the 20 black cables you need. A simple thing like having a variety of colours, perhaps relating to length (eg. green is 20m, black is 10m, blue is 5m and red is 1m).
If there is little cost difference (some provides don't make a charge for non-black) you might want to consider a mix of colours so that say Mic 1 is green, Mic 2 is blue, etc. This works wonders for when people cross and share mics and all you need to do is have the colours written on the channels which you can visually verify from a distance (sometimes electrical tape around a mic is too small).
Connectors
You'll obviously be aiming for a specific type of connector, for example 1/4 inch or XLR but there are a surprising variety of constructions. The main problem with multi-part constructions is that they are prone to failure. With instrument cables (1/4 inch) look for solid sheath ends (soldering isn't worth it).
For XLR cables there might be a case when you need to get into the cable, the best types are those that don't have seams along the length of the cable, rather by rotation the end is opened up. These allow you to do a gentle tighten without opening it up.
Impedence
Measured in Ohms this is basically a measure of how much resistance the cable will give to the signal passing through it. Low-resistance cables will provide a better signal particularly over a long distance, though only if its needed.
Oxygen-Free, Gold Coatings, etc
Unless you're doing something that requires awesome sound the standard cables will do you fine. You are more likely to find its cheaper to buy two standard cables for the same cost.
Gold-coatings can be beneficial on phono connectors, not so much because of better conductivity but because they resist corrosion and hence last longer, they also seem to stay cleaner. These can be useful on the back of a desk (in pairs) to ensure good connections with the desk and also 'banana clips' when using cables that don't have connectors on the end, eg. connecting to an amp.
Shielding
This is perhaps the exception to the rule of 'go standard', that is if you are finding a lot of interference from the likes of radio stations and hum and have tried electrical ground-lift solutions and checking cable coils then you may benefit from additional shielding on your wiring.
Impedence
Unless you're doing something that requires awesome sound the standard cables will do you fine. You are more likely to find its cheaper to buy two standard cables for the same cost.
Gold-coatings can be beneficial on phono connectors, not so much because of better conductivity but because they resist corrosion and hence last longer, they also seem to stay cleaner. These can be useful on the back of a desk (in pairs) to ensure good connections with the desk and also 'banana clips' when using cables that don't have connectors on the end, eg. connecting to an amp.
