You don't have to go to the grocery as often (you can have 30 meals on
hand in your freezer!)
You save money by buying in bulk
You save time by consolidating your cooking into one day
You eliminate the "What's for Dinner" worry
Your cut back/eliminate processed foods
You eliminate the cost of eating out

To get started you will need to take stock of how much time you have
to do your "cooking ahead".  It may be that you just want to
double the recipe you are cooking and freeze one batch.  Or you
could set aside a morning/evening to make a number of meals you can
freeze.  Or you may want to really go all out and do an entire
month's worth of meals at once.  This can take a good portion of
a day or two (with shopping and prep work) but the rewards are
outstanding.  Just think of how great it would be to have 30 days
worth of meals in your freezer!
Here's an important consideration - Most things freeze well but there
are some ingredients that do not freeze well.  If you're just
getting started in freezing your food you want to be sure you're using
recipes and ingredients that are going to hold up well in the
freezer.  For more information on what freezes well, check out
Freezer Meals 101.