If you're having trouble establishing a mind-muscle connection with your triceps then begin the workout with something that puts the muscle into a shortened position, and work isometrics (holding the contraction) to help with that. Try a pushdown variation. My favorite for this is the reverse-grip pushdown.
Make a concerted effort to roll your knuckles back towards your body and hold that for a 2-3 count for 3-4 sets.
A perfect warm-up virtually ensures a perfect workout, but a poor one will almost certainly ruin what COULD have been a great training experience. Ever wake up dreading the idea of going to the gym, but after getting there, you end up having a great workout? You can thank your warm-up for that.
A bar takes the ab rollout to the next level. Try a wide grip to hit the chest and shoulders as well as the abs. Have a super strong core? Narrow the grip.