which do i quit first??

Personally I would quit the things that are easier and then tackle that harder things later.

Some ideas that I have to help you in quitting these things would be:
fast food - pack some healthy snacks in a bag, I always pack a bunch when I go to work (carrots, raisens, a few graham crackers). These snacks would give your body much more fuel and you wouldn't want the fast food as much.
diet pop - switch to water, add crystal light packets to your water, iced tea is great (no the sweetened though). Drink diet pop as a treat.
coffee - no help here I have never drank coffee.
candy - if you are eatting chocolate and candy bars, try chewing gum or sucking on some sugar free hard candies.
going out to eat - use this as a treat. I always go to the restaurants menu online and see what I would be able to eat. Most restaurants have very healthy meals as well. If you want to give it up all together. Try to recreate there meals at home. You can cut down on the calories and save on the money side.

It all depends on your lifestyle which to give up first. For me it would be candy or diet pop.

Good Luck!!

My advice is to take it one at a time. Make a commitment to stop one every month, so you can focus and not feel like you're depriving yourself. I would pick whichever seems the easiest first. In the beginning, you need small victories! Also, make sure not to be too hard on yourself if you slip or have it once in awhile - it needs to be a lifestyle you can maintain permanently and if you always feel deprived - it won't last. Best of luck and Happy New Year!

i would also quit fast food first...if you like to eat on the run/in the quiet of your car, pack a well balanced lunch....also - i think that when you give up your fast food, your soda intake might also decrease (yay!)

I agree on the eating out.

You'll be amazed at how much weight a person can lose just by cutting out this ONE habit.

Saves booku $$$$$ too.

i honestly would do soda first. its suprising if you think about it how many extra calories your gonna have without drinking soda.

I cut out fast food. I thought about cutting going out to eat, but I still like to do that for the whole family. We like to sit around the table and talk, make an event out of it. The $$ issue was the reason we had to cut back, and I found that eating at a mid-range restaurant with the whole family isn't much more than McDonalds or Burger King.
Soda's a great one to to drop first though. It's just empty calories. I tried diet soda but it didn't do it for me. I had to go cold turkey. I'm still working on it, but one day at a time.... Plus my skin is starting to get clearer.