According to Britannica Online Encyclopedia, the workd Romanticism "emphasized the individual, the subjective, the irrational, the imaginative, the personal, the spontaneous, the emotional, the visionary, and the transcendental". Some people are born to be romantic, but some are born to be realistic and pratical. Its part of our personalities.

Being romantic is very personal thing as certain things are romantic to some but not the others. It's never easy to be romantic all the time as you need to make lots effort. However, in general, things like candles, teddy bears, red roses, chocolates, soft music, love poems, romantic movies, etc can help you to look romantic.

In short, you need to be creative and spontaneous. You can find more ideas in the following sites:
www.theromantic.com/
www.guardian.co.uk/travel/romantictrips