Today you'll be building your arm(y). The workout is nothing you haven't done before, so you likely already know how much weight you're using and how long the workout takes. Don't just rest on your laurels though. Being too comfortable and familiar with an exercise can mean you get lazy and sloppy.
Make sure you have a strong mind-muscle connection throughout every movement. Focus on making the correct muscle do the correct work. When doing triceps push-downs, keep your arms close to your body and perpendicular to the floor.
And, when you're repping out incline skullcrushers, keep the bar in line with your torso and your upper arms stationary and close to your head. Little mechanical improvements to your form can make big differences in your physique.