I would suggest to start with, just aim to meet the default fitbit goals (10,000 steps, 5 miles, and 30 active minutes, etc). That is where I started and then increased from that point.

Basically I don't ever enter exercise in MFP or fitbit (with the exception of biking/spin class) and just let fit bit do it's thing. I am currently trying to lose 2 lbs a week so that means I need a 1000 calorie deficit a day. Basically if I were to sit on my but all day and do nothing I would have to eat like 900 calories to meet that goal which is obviously not healthy and I never eat that little so I usually try to burn 2400 calories for the total day and then eat about 1400 calories. That has been working really well for me and I've been happy with the results.

Best of luck!

I would think that if you walked say 5000 steps leisurely vs 5000 steps quickly, that you'd burn more going quicker due to your heart rate rising. try to keep a brisk pace for 30 minutes a day and you should see some better results.