Great question. That's what I am frequently asked by those wanting to start loosing weight. The most important point is that you need to want to start. In the words of Napoleon Hill, "Desire is the starting point of all achievement, not a hope, not a wish, but a keen pulsating desire which transcends everything."
First, Know Where You Are Coming From.
Get a journal and weight yourself. Write it down and then check your weight every 2-3 days. Don't weigh yourself every day. This can be discouraging and many people fluctuate 2-5lbs every day based on meals and water intake.
What you should record every day is what you eat. Record your meals. If you are being followed by a weight loss specialist, they will want to see this. Record every thing you eat. And, record your water intake. I am amazed at how many of my patient's are dehydrated and just putting water back into their systems help them loose weight.
Second, Plan Your Day.
Planning is the key to weight loss on any program. You should plan your exercise and plan your meals the night before. Failing to plan is really just planning to fail.
Third, What's the Underlying Cause?
Loosing weight is possible. As a journey, it will probably have a number of components that will be necessary to make it effective for you.
Either way, enjoy the journey!!