Welcome and good luck!
I started exercising last year by doing the Couch to 5K program. I lost 25 lbs doing that and dieting (nothing drastic, just being smart) last fall and kept it off this entire year. In June, I joined a gym (something I thought I'd never do) and have been going three times a week at crazy-o-clock in the morning for a BodyPump (weight lifting/cardio) class. Have not lost any additional weight thus far, but have dropped some sizes in clothes back into the "regular" sizes.
Probably the best things I did to stick with this have been:
1) Food journaling. There are a bunch of great web sites and free smartphone apps that are easy to use. If it goes in your mouth, it goes in the journal.
2) Find a way to make yourself accountable. This is different for everyone. For me, it's telling my boyfriend or alerting my facebook feed that I'm going to the gym. My first 25 lbs was lost with the help of a 2 month weight loss challenge where I won $100
3) Become friends with your scale. The scale is not the enemy, but ignorance is definitely not bliss. Everyone is different here in the frequency of weighing themselves. I weigh myself every morning, just as a reminder of where I am and where I want to be. It's how I've maintained my initial loss this year, even off an official diet.
4) Invest in a good quality sports bra and good quality shoes. I got fitted for running shoes at a running shop and it was the best decision I ever made. In addition, a good sports bra will make exercise tolerable. Don't just go to Target and buy off the rack, do some research on brands and be prepared to pay a little extra-- but it's soooo worth it.
5) 3FC is a great resource. People here "get" it. So don't hesitate to chime in and make friends.