Have the food treat in an easily accessible location so that it can be delivered to the dog within three seconds and while the desired behavior is still occurring. I use a cotton waist apron, available from most hardware stores for minimal cost or on-line for under $10. A treat pouch or bag is better than a pocket, but can take some time to get used to accessing the treat quickly. After some training for both you and your dog using treats, you can transition to a pocket in your clothes. For most of us, getting into the picket for the treat, delivering it to the dog in less than 3 seconds is still a challenge. Remember that timing is everything!
Treats should be small and preferably soft and moist for ease of eating. A small dog should be given proportionally small treats. Remember to reduce the amount of food given at meals to allow for the extra calories given in training. Microwaved hot dogs, string cheese and pieces of chicken, beef or liver are all high value treats and should be used sparingly by combining one or more of them with your dog's kibble and/or cereal such as the round oat kind.