I have a novice question - with the huge array of fasteners available, how do you know which type is the correct one to use? Is there a chart that says if the wood (or metal etc) is X dimension use Y screw? Obviously if you need to screw or nail through 3 2xW members you need a longer fastener - but how is the diameter chosen correctly.
If you have a specific question e.g. How to fasten a grab bar to a fiberglass shower enclosure you will get a whole range of replies some better than others, but then it all depends on the specifics of a particular situation.