kanji - Should I use 竜 or 龍?

When writing the kanji for dragon, should I use the simplified or traditional or can I use either. My Japanese dictionary tells me that Japanese people learn both character forms in school. I know that the simplified version is more common, but I just think that the traditional versions look better. This question also applies for kanji that have a similar problem like 国 and 國.

Thanks for your help.