Getting a natural looking red

How is the best way to achieve a naturl loking red haircolor at home. I usually go to Sallys and use a copper red mixed with a little brown since it seems to go better since my skin tone is kind of tawny /warm. But hairdressers always ask me " Do you color it yourself or get it done". Is is that only fair skinned people with freckles look natural with red hair or am I doing something wrong. i can`t afford to go to a salon to get my hair done.

Thanks
Susannah