Yeah, actually, I take back what i said before. I think 伝えたい is better than 言いたい or 教えたい。

Thank you everyone for the replies, it helped me alot :)

Actually I'm using の as a softer sentence ender than よ. Sort of a soft, non-female version of わ (although I am aware of men using わ now, especially in Kansai region).

I don't think it sounds "too" feminine. I use it all the time in Japanese. Of course, I'm a pretty carefree, friendly, non-aggressive male, so it fits me well. It all depends on your confidence, situation, etc.

But I'll stand by my choice of の there unless a native tells me not to.

Yeah, 伝えたい is much better.

And I know the の isn't needed, but I opted to use it as a softer sentence ender. I'll defer to you, though, because your Japanese is far better than mine.

Perhaps since の functions like both よ and か, it was a poor choice of particle on my part.

Edit And yeah, about the なんか, that was way too colloquial (all my university friends used なんか like we use "like" in English).

I think the whole problem with your sentence is that it would be an okay thing to just say to friends... But you wouldn`t write it like that. Writing の as an ender looks feminine, particularly with that sentence. I find it hard to envision a guy saying that pattern. Not to say you can`t, but it just feels a bit strange.
Either way though, it wouldn`t be written - same with the なんか.

This makes me feel a lot better about what I posted. It felt quite natural when I typed it (admittedly, quickly while my fiancée was yelling at me to get off the computer so we could go to church—this was my mistake in offering half-considered advice).

I absolutely agree it sounds like something said to friends and not like something that would be written down. I hadn't considered that the card needed to sound any differently, but now that I've re-read what you've written, I find myself persuaded by you.

Regardless, I feel embarrassed by my initial offering, and relieved that I wasn't as completely wrong as I felt after reading your first post. The self-doubt has subsided to a certain degree. :)

(Whether the recession of my self-doubt is a good thing for JF, time will only tell!)