Combine garlic, oregano, lemon juice and red wine vinegar in a small bowl. Whisk in the olive oil and season with salt and pepper to taste. Set aside.
Cut chicken into 2″ pieces. Put the chicken pieces in a ziplock bag or in a shallow container to marinate. Pour marinade over the chicken, seal or cover and refrigerate for 24 to 48 hours, or whatever time you have. Just a few hours will be good if that’s all the time you have.
Heat the grill to medium high and cook the skewers, turning periodically for 10 – 15 minutes until cooked through.