I think there are many, many reasons to go to graduate school. Make sure you make the right decision for YOU, not what anyone else tells you.
Personally, I know I would regret not going to grad school. I am in my second full semester and am without a doubt gaining more knowledge, insight, and life experience than in undergrad.
For starters, class is WAY more interesting now, because they are classes I
want to take and they will be useful to my future career.
Also, if the opportunity is available to go to a different school than you did your undergrad, I would highly advise it. Just for the different perspective on things and the opportunity to grow as a person. I have learned more about myself and my abilities just by being out of my "comfort" zone.
It is important to go where you can get funding- it helps! Some schools may still require you to pay tuition, but you will get a monthly stipend that should cover that and living expenses- that's the situation I'm in, and it is totally worth it.
So enough of that!

If you have any questions PM me.
As far as preparing:
-take the GRE early;
-if you haven't already done so, start contacting professors that you would be interested in working with;
-visit the campuses and faculty you are interested in to make sure you like the "feel" of things.
-email or call other grad students in your area of interest at the university you are interested in. This info is generally avaiable on the departmental website. Just getting input from current students helps and they may be able to give you some "inside" info or advice.
Hope this helps! Good luck with your "quest for knowledge"!