Get a Better Mix
It isn't enough to collect all the elements called for in your script. That's mostly an administrative job. The art comes in the mix.
Here are two common problems: Effects run amok and ineffective EQ.
You can often tell when a radio station has received a new CD of sound effects. Every other spot on the air is full of noises that may not support the concept of the spot. A spot like that is fun to produce, but if the client doesn't sell any widgets, you won't see their money again. Another problem with effects is level. They are often too loud. Take them down until they really are too soft and then bring them up just a bit. Now you'll have elements which support the rest of the audio rather than dominate it.
A few thoughts on EQ: First, it's better to lower unwanted frequency ranges than raise wanted ranges. One of the most common uses of EQ is to brighten a VO. Consider "dulling" the music or effects track instead. Really. Try backing off your music 3 or 4 dB at about 6k and see what you think. You'll get that denser mix without too much harshness. Can't bear to do that to a jingle? Put the jingle on two stereo (or four mono) tracks of your multitrack and EQ the 6k trough in one. Use the effected track for the bed under the VO and cross-fade to the straight track for the sing. Just make sure the two versions line up exactly in phase.
Second, let's think about bass on the air. It sounds great in the control room to have a big voice on a large-diaphragm condenser mic and then mix in a music track with a huge low end. Remember three things:
1. Bass uses a lot more energy to produce the same apparent volume.
2. Every spot on the air gets the same amount of energy through the station's processing. Many stations even process frequency bands individually, making everything on the air conform to their station "sound".
3. Most radio and TV listening is done through the equivalent of clock radio speakers.
Do you want to squander your allotted energy on bass few people will hear? You may actually end up sounding softer than surrounding spots.
With EQ, concentrate on getting an intelligible message across. That way, maybe the client will sell a bunch of product and come back to spend more money with you next month.
To apply these ideas to industrial audio, just imagine the folks gathered in the employee break room watching a training video on a 12-inch TV with a two-inch speaker.