One of the tips I tend to give guys in the gym when they ask about training calves is footwear. Most trainers / sneakers / whatever you want to call them tend to limit your range of motion in my experience. Try either of the following:

Barefoot / socks only. Lots of old school BB'ers like Arnold etc did them barefoot.
Buy yourself some rock climbing shoes. They're great for squats and deadlifts too.

I climb, so discovered this just thinking "I'll try it". My calves have improved dramatically as a result.

Twice a week for me. Higher reps on seated calf raise day 1, then lower reps on standing and donkeys day 2 (usually 3 days apart).

Sometimes I like to do stair stepper for 10 mins to get the blood flowing in the calves. Then immediate walk over to the seated calf raises. 2-3 plates do 5 bottom half and 5 top half and 10 full reps.

do this for 5 sets then walk over to standing calf raise machine and do the 5+5+10 but 3 sets. One set do toes pointed together and heels out, 2nd set toes pointed out and heels touching and 3rd set toes and heels touching.
then put like 200-300pounds on it (heavy to were you can only do 5-7 reps) and do 2 sets of heavy weight reps of 5-6

then I like to go on the seated straight leg calf extension machine (forget what its called) and I do 3 sets of 15 reps really heavy

make sure to stretch!! I do this 2-3x a week

My calves are hard as hell to grow. I try to hit them with heavy ass weight. Lately I have been doing a lot of drop sets. Pyramid sets also work for me. I have seen some results recently. You just got to pound them hard.