First thought on a plan to increase pec size is to prioritize. On First day of the training period when fresh and ready to go, that is day to hit the chest. Once a week, or twice a week is up to you. If your going to hit it once that week, I would do 3-4 exercises 3-4 sets each. If twice a week, do 2-3 exercises. -since your just starting out I would right down a plan and stick to it for at least 2-3 months. Focus on pushing your self to lift more weight and get stronger. Hopefully you'll get to point not knowing what your going to do when you get to the gym, but by instinct you pick the exercise to do. - Their is alot of exercises to do I would recommend just picking 2 power exerices and 1-2 fly exercies. I do bar exercises one week,dumbbell exercises the next. Also, if you look at the muscle,the fibers run sideways, that is were fly exercises can work well to hit the pec region and isolate. - Finally, the power of motivation,and the will and excitement to workout andgrow,can help increase your goals tremendously. Love to workout and train and everything else will come into play.