walking tips

Set reasonable expectations for your progress
Find a good place to walk
Make an exercise music playlist
Develop a strong mental attitude for "slow but steady" exercise
Hydrate well before you begin walking
Pick an easy first walk
Set a time
Increase your time
Work on speed and difficulty after you are able to walk for 45 minutes each day
Determine your target and maximum heart rate. Determine your target and maximum heart rate
After you've worked into a general routine, try switching things up with interval training

warnings

Before undertaking this or any other exercise program, be sure to check with your doctor, especially if you haven't been physically active in more than 6 months.
Be prepared for your walk. Take water with you. Also take along a whistle in case you get into trouble with dogs or unsavory people. Carrying a cell phone is also a good idea.
If you are walking and become short of breath, slow down or stop. Ask for help if you need it.
Don't carry weights with you as you walk. This extra weight throws your gait out of balance.
Be sure to wear proper footwear. Sandals, flip-flops, and even fashion athletics do not support the various muscles, tendons, and joints in your foot and can therefore cause strain and injury.
Although using an mp3 player or radio can make your walk more interesting, it also makes it difficult to hear things around you, including potential hazards such as oncoming traffic, would-be attackers, and animals. If you like to listen to music or books while you walk, keep the volume moderate and be aware of your surroundings.
Wear white clothing and reflective fabrics if you will be walking at night. Don't assume that drivers are paying attention or that they can see you after dark.
Stretch before you walk just in case

A water bottle - Drink water during walks of ten minutes or more whether you feel thirsty or not. (Yes, this applies to cold weather and warm weather.) Dehydration can lead to dizziness, blackouts, and even death.
Good, comfortable walking shoes or sneakers and thick socks. If you have thin socks you may get blisters.
A cellphone for emergencies.
A whistle to call for help should you run into trouble of the criminal type.
A hat and sunblock on sunny days.
An MP3 or cd player so you can listen to music while walking.

Source: http://www.wikihow.com/Start-Walking-for-Exercise