Monitoring yourself while recording
One of the most important factors in getting a great take is Performance. Good performance requires confidence, focus and comfort and these cannot be achieved if you can't really hear what you're doing.
I find that using headphones can be a bit uncomfortable (especially if you like to move around while recording) and the main reason for that is that headphones can make you feel isolated and prevent you from hearing yourself in a natural way.
If you feel that you can't really hear yourself or that you are having problems preforming well with headphones I'd recommend trying one of the following techniques:
1. Use your headphones only on 1 ear and keep 1 ear free - this will allow you to hear yourself directly and will also enable you to sing or play over fairly low playback levels which is much healthier for your ears.
2. Don't use headphones and listen through your speakers instead - this technique gives you a lot of freedom if you like to move around and from my experience is ideal for recording guitar, bass and keyboard. If you're going to use this technique I highly recommend to keep your microphone gain and speaker playback level fairly low in order to prevent feedback and reduce the amount of bleed that goes in to the recording, there's no way to avoid bleed with this technique but its definitely worth it if helps you preform better.