Try First

There might be worse things than spending the time to make a full-blown meatloaf only to discover that it doesn't have enough salt in it, but I can't think of any off hand.

Here's the trick: when making meatloaf, sausage, or meatballs, take a small chunk of your mixture and fry it in a skillet (or even faster, microwave it for 10 to 15 seconds) and taste. Adjust seasoning levels in the mixture accordingly.