In this article I'll cover the standing preacher bench curl.  For this exercise I recommend using a curl bar because it will be more friendly on the wrist and instead of going to the wide grip like you would for the standing curl you'll want to place your hands on the narrow grip.  Now one of the great parts about this exercise is that if you don't have a preacher bench around or if people are hogging it at the gym you can adapt and use other pieces of equipment as well, oftentimes if the preacher bench isn't available I'll use the hyper extension bench as a preacher bench and it serves just as well. 

Regardless of what type of bench you end up using you'll always want to make sure that your arm is right on top of the pad, focus on not getting too far forward or too far back you want the top of the pad right underneath your armpit.  Once your arms are in place get your feet situated, I usually place both of my feet just underneath my elbows which is a little further forward than you'll normally be used to.  

Once your arms and feet are situated it's time to start with the exercise itself.  With a nice tight grip start lowering the weight down, focus on having a nice slow motion and having a three count down.  Once you've reached the bottom, pause for a second and take a nice deep breath in and then lift the weight up.  As you bring the weight up exhale the deep breath that you took at the bottom  it's important that you stop once your arms have reached about a ninety degree angle.  If you lift the weight up further than that you'll lose constant tension on the bicep and you'll run the risk of having the weight fall back towards your face. 

During each rep focus on exhaling as you let the weight down nice and slow, once the weight is down take a nice deep breath in first and then lift the weight up to the ninety degree angle.  At the top of each rep focus on squeezing those biceps, getting a nice isometric squeeze at the top of each lift will assist in getting the absolute most out of each rep.

A unique technique that you can use on your last few reps when your body wants to start moving around to gain a mechanical advantage focus even more on exhaling and driving your knuckles down to the floor at the bottom of the movement because that's going to lock your armpits right down on the preacher curl bench and make your last few reps extremely powerful.  Another thing to do is on your last rep add a 5 second negative with a nice stretch at the bottom. 

If I'm by myself and don't have a spotter I just let the weight down on my fingertips, I start to stand up and then just pull it up on the preacher bench.