Think of a base and look up what highlights or contrasts it. Red or Blue calls for black or white, or maybe brown to beige. Green when dull calls for browns. Orange calls for black more than white, some darker blues or jeans too. Purple and violet like green, or grey or beige. Pink goes better with white than black. If you want several look at how flowers combine the multiple colors (besides all the green). Those are the combinations that generally are enjoyable to see.

Edit: I just wear black or blue as a base and add red as highlight most of the time. Red shirt. Red belt, white and red shoes. And for whatever else I have specific outfits I don’t mix with anything else. Somethings I look like a metal head with band shirts and long hair. The next day you’ll see me wear basics and light jeans with a straw hat.