Updating your profile picture should align with significant changes in your life or brand. If you've gone through a significant transformation or redesign, it's a good time for an update. Otherwise, once a year is a good rule of thumb.
Experiment with filters and effects to find the style that suits you best. Remember, subtlety is often more appealing than excessive editing.
While logos work well for business accounts, personal accounts benefit from a clear photo of your face. People connect better with faces than with logos.
Filters can add a unique touch to your image, but don't overdo it. Subtle enhancements are more appealing than strong filter effects.