Yes, as Donna said, Music Library Report is a great place to start. Itís okay to record in the 24-bit zone, but save to 16 bit/ 48KHz (the Industry standard). Some libraries won't accept anything else.
Keep in mind... the music libraries are bursting at their seams with music, so be very particular with what you submit. Finding a niche of your own will get you noticed. Create something different that sets you apart from others. Sending similar tracks as others, will get your music lost in the jungle. That being said, thereís power in numbers. If you have a thousand tracks in a library, youíll stand a much better chance of coming up in a music search, than if you only have a couple. Although, a couple great tracks are better than a thousand crappy tracks. Be careful how you title your music. Use at least one descriptive word in the title, that is likely to show up in a search.
Spread your music to several libraries until you find one thatís working for you. Non-exclusive tracks are fine, but Iíve found out youíre treated better by the library in the exclusive arena.
Another point, most libraries have their own in-house composers. They have the edge over the big gigs. Thatís why itís important to have your own niche different from the main stream. Find something the in-house composers donít or canít do.
And above all Ė love what youíre doing! Anything less is a big waste of time. Good luck! Yes, that's needed as well.