With the Side Plank alignment is very important in this one everything needs to be straight.
As with plank this can be done on a bent arm with elbow on ground or straight with palm on ground your choice.
Lay on your side make sure that the body is in a straight line.
Pick your arm position.
Feet you have the choice top leg directly on top of bottom so that feet are together or bring the foot slightly forward to help with balance.
This can also be done with the lower leg bent on the floor until strength builds.
As you breath in lift the hip off the floor you are again looking for a straight line no dipping.
Take the top arm up and face palm to the side you are looking make sure that you open the chest and shoulders and arms are stacked.