Allow the user to customize the appearance of the application by providing several color selections for background and foreground. Choose those selections with settings for a range of High Contrast selections in mind. Avoid Reds and Greens together. Yellow on Black are high contrast settings. Testing Test the software to ensure that it complies with accessibility requirements.
Several techniques are available.
For Windows software, turn on the high contrast setting, and check that your application respects that setting. Test at least two color settings and two high contrast settings to ensure the software is not dependent on a particular setting.