Can't beat the advise from the more experienced postings but your question hit close to home.
Start: I was 5'-11" and 250lbs (yikes!!) with bodyfat around 25%
Now: Same height (thank god!

) 218lbs with bodyfat around 13%.
How did I do it? Here goes a summary. . .
1) Overtime remove all food from your home that promotes poor nutrition (cookies, ice cream, chips, 70% lean hamburger, etc.)
2) Encourage all family members to improve their daily nutrition. Don't force but your actions will help them to eat healthy.
3) Try to eat every 2-1/2 to 3 hrs. Smaller meals and combine quality lean proteins (skinless chicken breasts, salmon, etc.) with complex carbohydrates (brown rice, small potatoes)
4) Get at least 8 hrs of sleep!!! If your dragging or lacking motivation then this is probably the issue.
5) Think long-term lifestyle change! Don't look at this as "I want to lose 20lbs" think along the lines of "I will lose 5 inches around my waist and gain 1-1/2 inches on my chest and arms."
6) Keep the forum posted with your progress! This group really cares.
7) Get checked by your physician. You need to know if your blood pressure, cholesteral, and blood glucose are normal or need improvement.
8) Take before and after pictures (front, side, & back)!!!!!!
9) Once a week, give yourself a free day.
10) Cardio is good for improving circulation and cardiovascular strength. Check out Body For Life to read about the high point technique.
Good Luck!