Calves are a pretty stubborn muscle group for most people so using full range of movement on this exercise is important.
1.Firstly make sure you are keeping your legs straight. No bending at the knees or hinging backwards and forwards through your hips.
2. Don’t put too much weight on as i find alot of people lift through their shoulders if its too heavy.
3. Legs straight.
4. Toes pointing forward(although a variation of toes in or toes out is good to mix it up)
5. Heels all the way down. Feel that stretch and hold for a second.
6. keeping legs straight, go up onto the balls of your feet. Once you think you are at the top push up a little bit more( its like a 2 stage thing) but i guarantee if the weight isnt too heavy you will still get another few cm of movement. Hold that squeeze and slowly lower down.
7. Remember – Time under Tension
Hope this helps