If you're a fan of stay-in clothes which are stylish enough to wear out, you should consider this pairing of a burgundy crew-neck t-shirt and black sweatpants. Finish your look with black leather sandals to switch things up.
Black Sweatpants with Black Leather Sandals Warm Weather Outfits For Men
If the situation allows relaxed dressing, go for a red blazer and black sweatpants. Black leather sandals will add a more casual feel to an otherwise classic ensemble.