There are many different strategies that can be effective for altering habits. 

These 'habits' which I'm addressing are not to be confused with addictions. Addictions include habitual activity, but are much more in scope than merely a quirk we would like to  address in our personality. In fact, addition is in the abnormal section of the psychology library. 

There has been a disturbing amount of  refrains and reiterations with addition and PTSD treatment. Troublesome refrains. Dangerous. For example addiction and habits are often addressed through the objective awareness of trigger events which reinforce the unwanted activity.  However, avoiding triggers is a symptom of PTSD -- not a treatment. 

Quirks or not, habits can be tenacious and bothersome all on their own.

Here are a few ideas:
  1. Identify the triggers that lead to the habit: In order to change a habit, it can be helpful to understand what triggers or cues lead to the behavior. Once you have identified the triggers, you can try to find ways to modify or eliminate them
  2. Set a specific, achievable goal: It's important to have a clear goal in mind when trying to alter a habit. Make sure that the goal is specific and achievable, and that it is something that you are motivated to work towards.
  3. Start small: It can be overwhelming to try to change a habit all at once. Instead, try starting with small steps and gradually increasing the difficulty.
  4. Find a substitute behavior: Instead of trying to eliminate a habit altogether, you may find it helpful to try to replace it with a more positive behavior. For example, if you want to stop biting your nails, you could try keeping your hands busy with a stress ball or fidget toy.
  5. Get support: Changing a habit can be difficult, and it can be helpful to have support from others. You might consider enlisting the help of a friend or family member, or joining a support group.
  6. Be patient: Changing a habit takes time, and it is important to be patient with yourself. Don't get discouraged if you don't see progress right away. Keep working at it and you will eventually see progress.