Meditating correctly may not be the correct term, as everyone's experience while meditating may be different, and everyone may have a different pace at which they see the benefits or feel any difference from meditation.
Think about what your purpose is for meditation, and then try to understand if you are reaching those goals. Is your goal to calm down? If so, has meditation helped you calm down?
If it has not, then you could ask yourself why it hasn't, maybe you haven't given it enough time. Meditation is a practice that takes time to actually get good at, meaning, for you to actually get into the mindset, to be calmer, relaxed, and to help reduce stress and anxiety, and all of its other benefits.
If you have not given it enough time and practice, then you may actually be doing it correctly, just not long enough and not often enough.
I would say that one of the few ways to not meditate correctly is to expect the wrong things from meditation.
It's not a miracle, it's not a fast fix or a cure. It is a practice, something that can take a long time to reach the goals you are trying to reach.
Also, if you meditate once in a long while, then that too would not be an effective way of meditating. You should try and have a consistent practice, and to meditate as often as you can. This does not mean that you need to meditate everyday multiple times a day for hours, but even just a few minutes per day will do it and get you a long way.
Other expectations that some have, are to have clear minds when meditating. They expect their thoughts to just go away as soon as they start meditating. This is an expectation that is not realistic, and expecting this will just harm your practice, as this most likely will not be the case.
So just meditate often, and don't expect things that are not realistic. Just be in the moment and focus on the meditation, on the breath.
