I am 36 and had my first tattoo in my teens. As well as having 14 tattoos from various artists over the years I am in the process of becoming a tattooist myself.
In answer to your question; If you are unsure whether you want a tattoo or not, I would advise against it. A tattoo is with you for life and although fun, it's entertainment value may decrease over time.
If you DO end up getting inked, I would suggest that you think long and hard about the design, possibly going for something that will ALWAYS be relevant to you.
I hope this helps.