The elbow flexor group is made up of the biceps brachii, brachialis and brachioradialis. As well as elbow flexion, the biceps acts to aid in shoulder flexion and also forearm supination (along with brachioradialis). To effectively hit these muscle groups, we just have to do one thing; flex the elbow under load. It really doesn’t make too much of a difference what variations we do, but some are slightly better than others; namely the incline dumbbell and standing dumbbell/barbell curl (Oliveira et al., 2009). One good cue to increase biceps activation, is to start with the arms fully pronated (palms facing away) and end with them fully supinated (facing towards you).
The elbow extensor group is made up of the triceps brachii and the anconeus. The triceps have 3 heads: medial, lateral & long head. All 3 are strong extensors of the elbow with the long head aiding in shoulder extension & adduction. The close grip bench has shown to elicit high activation in all 3 heads of the triceps (Saeterbakken et al 2017, Lehman et al 2005). Since the triceps are slightly fast twitch dominant (Srinivasan et al 2007, Johnson et al., 1973), training with higher speeds & heavier loads may be beneficial & the close grip bench is perfect for this as it can be loaded heavily in the 4-6rep ranges. Next is overhead extensions, which has you in shoulder flexion & EMG data has shown this to be one of the best exercises to activate the long head of the triceps (Boeckh-Behrens & Buskies 2000). Lastly, a pushdown movement, which will effectively hit the lateral head of the triceps.
In terms of volume and frequency, Schoenfeld et al. (2016), found that twice a week per muscle group to be most efficient for hypertrophy, but they were uncertain if 3 times was any better, so if you personally find 3 times a week to be best, stick to it. I like to load one exercise heavy (4-6 reps)nd the remaining exercises in the 8-12 rep range, always applying progressive overload