Naked Feet Work Better
Deadlifting barefoot or in socks:
- Alleviates an anterior weight shift.
- Helps to shift your weight back.
- Better engages the posterior chain (glutes/hamstrings).
- Gets you closer to the floor, which equates to a shorter distance to lockout.
If you train at a gym that doesn't allow you to take your shoes off, it's lame and you should consider finding a new gym. Shy of that, look into purchasing a flatter shoe like Chuck Taylors.
When doing deadlifts barefoot, it's a good idea to adopt the concept of active foot vs. passive foot. It was initially devised for squats, but it carries over very well to the deadlift, too.
Active vs. Passive Foot
A common mistake people make with their initial setup is losing the arch in their foot so that it flattens out and collapses, resulting in a disadvantageous position. The easy fix is telling someone to wear orthotics (and, true, some people require them). However, orthotics are often a lazy fix that doesn't address the actual problem.
Adopt an active foot instead. You'll learn to get even weight distribution amongst three contact points of the foot – underneath the big toe and little toe, as well as the heel. Additionally, you'll "layer" the three points of contact with another popular cue, which is to corkscrew your feet into the ground as if trying to rip the floor apart. This helps to improve external rotation torque in the hips, drastically improving hip/low back stability.
Make a Heel Print in the Floor
The deadlift is just as much a pushing exercise as it is a pulling exercise. You need to think about pushing the barbell away from the floor by putting as much force into the ground as possible.
A common cue is "try to make a heel print in the floor," and it works like magic. Not, like, you know, Gandalf defeating the Eye of Saruman magic, but more so like, "Holy shit, I just lifted 20 more pounds than usual" magic.