If you're terrible at matching colour combinations in clothing (or you're just colour blind), you have two options: Stick to the essentials (black, grey and white), or grab a friend who's colour-savvy and have them act as your "style spotter".
Aaron, aka "Alpha" from I Am Alpha M, explains the process in the video above, in response to a style question he received from a viewer who is colourblind. Then (at about 3:23) he offers some specific advice for people looking to make sure their wardrobe matches and looks good even if they can't see or tell the difference between the colours or shades themselves.
Sticking to neutrals is one way, but it can be a bit boring. Instead, grab a friend who's colour-savvy and have them come with you to help you out. He likens the idea to getting a spotter at the gym. Ultimately, this boils down to "take a friend you trust when you go shopping", something you might do it anyway, but it's a solid reminder that we're not always the best judge of our own style.