Dress conservatively. Avoid the latest fashiontrends at all costs. If you are a guy you should wear plain pants that should be pulled high and not come down to your shoes. Girls should wear long loose fitting clothing. Your hair style should never attract attention and you should spend very little time making your hair look nice.

Play video games as often as you can.

Add nerdy accessories if possible. Bow ties and pocket protectors are not nerdy in and of themselves but they are often a part of the equation.

Be a messy clumsy uncoordinated person. Try to drop things, forget things and trip on things whenever possible.

Spend all of your spare time learning or studying. Don't spend your time with friends or going to parties. Be anti-social.

Stop playing sports. You should prefer read or study over physical activity.

Wear glasses. Glasses are not nerdy, lots of people wear glasses that are not nerds. But glasses are another piece to the puzzle.

Have attitude that shows you are a nerd. Talk about meaningless facts that people do not care about. Instead of having people over or going out to do something fun ask people to help you with a science project or research your latest idea