just a few things
radiorickm <- been there & done that.
first thing. talk to the station you are going to send the cm to. some stations want cd, some tape, some wav. make sure you get them what they need.
also on that point, there are a couple of timing things you need to check. most stations i have worked at want exact legnth cm's. meaning you should make them EXACTLY 30, 45, 60 what ever they want. this is really inportant in the digital/computer cotrolled world. However, i did work at one station that used odd legnth, like 47 seconds. made backtiming songs a pain in the ass!.
remember that the content of the commercial, or the speech part is the most important to the advertiser. it is the part that must come across best. the music is just fluff usually, or the hook.
i used to record cm's in what i called a "U pattern". in the beginning, the music track was loud, then it fades for the voice over, the it rises again at the end. you gotta make the info fit into the dip in the "U".
you can listen to the background music and put your speech into a "sympathetic pattern" or speed your voice to the music. also, when you take a breath, try and get back in on the 1 count of the music. sounds more natural.
well, good luck in your endeavour.