I think, being yourself and trying really hard not to ruin your and your partner's day is a feat in itself. There's actually no need for expensive dinners, all you need is to spend quality time with your valentine - pay special attention to him/her and his/her needs, talk in a softer voice, be extra sweet, do little things that you know he/she really appreciates and that will be one of the most memorable valentine's days of your lives together.