A short list of simple things that may be holding you back.
Tonight I realized that, in over a relatively short period of time, I had taken my broken-ass deadlift from shit... to fucking awesome. So I thought I would share some thoughts with everyone on how I got there. This list is excellent for beginners, but even if you're an experienced lifter, you may be overlooking something.
1. Don't be a pussy
Yeah, the deadlift sucks. But it's a true test of your posterior chain (the muscles on your backside). If you're serious about being big and/or strong, you had better do some deadlifts.
2. Technique
Study good technique. Don't just watch YouTube gym gurus. Instead, watch professional powerlifters and bodybuilders perform all sorts of deadlifts. If they're pros, they're doing something right.
Have someone smart watch you. Sometimes this involves videoing your training session and posting it on Facebook and YouTube—where every asshole can post about it. But if you don't have people keeping an eye on you, it's very easy to slip into bad habits.
Practice makes permanent. If you practice bad technique, you will be plagued with bad technique. I will not deadlift for reps of max effort if I do not have someone smart watching it.
Technique is half the deadlift. If your technique sucks, you will get hurt and are shortchanging yourself.
3. Lighten the load
Leave your ego at the door. Sometimes (a lot of the time) you need to lighten the weight and do more reps. This follows Tip #2: if you can't do 10 or more reps with excellent form, something might be wrong.
Deadlifting heavy is taxing on the CNS. If you go heavy too often, your gains will eventually suffer. I've learned this myself and so have many of my training partners. Don't learn it the hard way.
4. Speed
The other half of the deadlift is explosiveness. With very few exceptions, the deadlift is a two- to three-second lift, and every second after three, your odds of locking it out decrease exponentially. So do some research on the various methods for becoming more explosive. The dynamic effort method is most widely used by power athletes but is really just another form of plyometrics. If you are not explosive, your deadlift will suffer.
5. Your core is weak
Your core isn't just your abs. Your core consists of your abdominals, obliques, spinal erectors, hips, lats, and traps. If your deadlift is struggling, strengthening and conditioning all of these muscles will increase your lift even if they aren't the main culprit. Having a stronger core will also make all of your other multi-joint lifts stronger and better, so just do it. (Oh, and refer to Tip #1 and remember that a six-pack does not always equal strong abs).
6. Your grip sucks
Having a strong grip is a necessity when deadlifting for a lot of reps or with heavy weight. However, sore forearms and feeling like you can't hold on to the bar is very psychologically damaging and may hold you back. Plus, we could all use a stronger grip and it benefits every lift, so why not do it?
7. You need better conditioning
You need to have the energy to get work done. One thing I began to notice was that I was burning out by the end of my warmup. My conditioning was shit, and it was keeping my deadlift in the mud. So, sometimes it's beneficial to lighten the load and do more reps (See Tip #3). Also, every now and then cut your rest time to really annihilate yourself. The deadlift is very taxing on your body and regardless of the intensity of the workout, you'll probably be feeling dead after it.