Natural Light
Take your pictures in natural light whenever possible. Diffused light is the best lighting situation. This is the kind of light that is present on an overcast day. The sun is hidden and not shining directly down and the clouds are creating a soft box effect by distributing light evenly across the expanse. In this type of shoot, no flash is usually needed as the light is soft and free from shadows.
Find a shady spot when the sun is shining at its fullest. It could be under a big tree or in a gazebo at a public park. Keep a diary of locales that have consistently good lighting and go back over and over again.
Reflectors
Using reflectors is the simplest way to manipulate available light. Your main light source should be behind and over the subject's shoulder. It's never a good idea to have the subject looking into the light. This creates uncomfortable squinting and harsh shadows. Instead, use a reflector to bounce the light back onto your subject. Place a mirror or a white foam board at an angle in front of your subject. This creates a soft pleasing light. Professional reflectors are available at photography supply shops and online. See Resources below.
Studio Basics
Setting up studio lighting doesn't have to be expensive. Start out with a few necessities and build on your inventory as you go. A couple of florescent lights are a good beginning. Keep that reflector handy and invest in a softbox to distribute the light evenly. Purchase several yards of muslin to use as a backdrop. This material can be dyed and painted to suit any occasion or skin tone you wish to match. White muslin can be also be used to create light against a dark wall.
Learn the basics of lighting and you will get the shot you're after every time.