How much salt should I add to a dish?
I've noticed that salty food has somewhat of an addictive quality; people who eat a lot of it (i.e. fast food or other processed food) tend to bury their meals under a mountain of salt, whereas people such as myself who do a lot of home cooking hardly use (or want) any.

"Season to taste" means pretty much what it sounds like; add however much salt (and other spices) that you, personally, like the taste of.  If you have a habit of eating a lot of salty foods, then you might want to add a little less than that, for the benefit of people like me who gag at heavily-salted foods.

If you use a lot of other spices, you won't need much salt - a few shakes of the shaker is enough.  If the food is basically bland aside from the salt (and maybe pepper), then you'll need to use more.  The best thing to do is add a little, then taste, and repeat as many times as it takes to get the flavour you want.  If the food you're seasoning is still raw (and can't be eaten raw), then just put in a small amount the first time you make it and keep track of how much table salt you needed to add.

Just remember, you can always add salt later, but a dish that's too salty is permanently ruined.