As clichéd and old it may sound, follow the basic tips. Start by showering every day—twice if it is summer and you take part in some physical activity. Maintain your hair and beard. Trim regularly to keep them in proper shape. Avoid the scruffy look. Also, always (always) keep an eye on your nose and ear hair. Keep them clean. Your neck hair, shave it whenever it grows.
Use the right shampoo, face wash and body wash. Even when you’re not going out, apply sun lotion + moisturizer. It will keep your skin healthy.
Keep your nails (hand and feet) short and clean. Brush twice daily! Floss at least once every day. Keep your mouth clean and fresh. If needed, invest some money in mouth freshener. Also, buy a good lip balm and body lotion.
Coming to clothes, avoid the hippy or emo appearance. Pick only the right fit apparels. And also wear only things that you’re comfortable in. Make sure the clothes are clean and well ironed.
And now the most important thing – how you smell! Always use a good deodorant. Next, apply some light cologne on your wrist and rub it on your body. Your scent can either make or break the deal for you. So be very careful and selective of your fragrance.
These are the basic grooming tips a guy in the 20's should follow. Remember, it’s not as much about what you use and wear. It’s about consistency. You must do these every day to make sure they make a standard and noticeable result, standing you out from the crowd.