Best exercises for a heavy girl?

Dancing is an awesome workout. If you're enjoying it, keep doing it. There isn't any one exercise that works for everyone (based on what individuals enjoy, not results).

And maybe try incorporating some weight training, as well.

pretty much this. if you're having fun, you'll stick with it longer.

weight training is a beautiful thing! if you've never done it before, then get a session or three w/ a trainer so that you have someone showing you the right form (you can ask for this for your birthday and have everyone chip in, if you can't swing the expense). but you will never regret lifting.

Thanks! I really love your advise! I will definitely stick to the dancing and will try to incorporate squats , how many sets and reps do you suggest?

3-5 sets, 5-10 reps. Enough weight so that you fall into that rep range... light enough that you can do 5, but heavy enough that 10 is a struggle. Focus on your form at first, then go heavier as you get better with the movements.

30 day shred by Jillian Michaels is my fave. I loaned it out and have used her butt and thigh one.
I plan to do p90x but it is kinda a scheduled confusing thing and a bit longer than 1/2 hour like Jillian Michaels.
I have insanity too, but that is a long term goal.

Fo Sure I would do Jillian Michaels first.

For a total beginner who is very overweight, this isn't advisable. She has NO IDEA on what good form is and doing plyometrics and squats with bad form will lead to knee, ankle and joint issues. It's one thing to watch a video, another to actually perform them correctly.

A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 28+ years and have studied kinesiology and nutrition

I agree. Also, if you are completely unconditioned, you'll never make it through the warm-up.

OP, your stats are close to what mine were when I first started. I began with walking and calisthenics (jumping jacks, push-ups, etc). After I dropped to about 250, I started the Couch to 5k program. It's a great program for beginning fitness.
http://www.coolrunning.com/engine/2/2_3/181.shtml

On the beginner Jillian Michaels she shows proper form, what not to do and modified moves in case you aren't capable of the full move or are a beginner. She also says you can start with no weights or build up to make the workout harder.

So, Jillian Michaels really is a great beginner video since she is VEry Very thorough and safe In fact, after watching a few times I wish she seperated out the training from step 1 since I have caught on.

Like ninerbuff said, there's a difference between watching a video and actually doing the moves. My old roommate, for instance, had terrible form despite the trainer on screen in front of her instructing. (ex: bicep curls she would move her elbows forward) Whenever I tried to correct her, she would say "But I'm doing EXACTLY what they're doing!" Um, no you're not. It took an actual trainer at our gym to teach her correct form to do the exercise properly.

Sometimes you can think you're doing something right and not realize it's totally wrong.

In Feb 2012 I started out at 270 at 5'4". I have bad knees so I just started doing the Leslie Sansone Walk at Home dvds. 1 mile in 15 minutes and 2 miles in 30 minutes. You might try that or just walking outside before or after work or on your lunch hour. I love Just Dance also and have fun with it too. Pick something you like to do and enjoy.
I did start running a couple weeks ago but now my knees are killing me so I think I will not be able to continue that type of exercise. I went back to walking 2 miles in 30 minutes today before work and usually walk another 2 miles in 20 minutes on my lunch hour.
Be careful and start out slow and build up.
If you are able to join a gym and have someone show you how to use the machines that helps too. Planet Fitness is opening up in my town and I joined in Dec and they open next week and I am so excited to start there next week. I have never went to a gym so it will be learning experience for me. They are very reasonable $10 a month with no contracts is why I joined. If I don't like I am not tied into any contract.
Good luck!

I'm over 300, and started on a recumbent stationary bike. It's extremely helpful because it supports my back and is easy on the joints (plus I can catch my TV shows while I work out, which helps me to go longer/stop watching the clock on it).

Thank you for this post!!

*takes notes*