So maybe you should consult with someone that knows how audio should sound and knows how to achieve it. If you don't have access to such a person, perhaps you can start with the following to get started.
For the Expander, turn on room noises like air conditioning, then set the Expander threshold so that while the announcer is close to the mic, but perfectly quiet, you have 9 to 12 dB of gain reduction on the meter. Try a ratio of about 12:1. The idea here is to keep down room noise when the announcer's mic is open but he's not talking. If you hear the expander "jittering" adjust the threshold for more G/R.
For the Compressor, choose a mild ratio like 2.5:1 or 3:1. Set the threshold so that when the announcer talks reasonably loudly, you get 9 dB of G/R. When the announcer talks normally, you get about 3 to 5 dB of G/R.
De-esser: Set the freq about 6 kHz. Make loud hissing noise into mic. Set threshold for 3 dB of G/R.
EQ: Some like to set the Bass EQ to "peaking" (not shelving). Set Center Freq to about 80 Hz. Boost by 2 to 4 dB. Deep-voiced announcers will likely need this flat. Depending on the mic, set the High EQ freq (shelving) to about 10 kHz and boost 1 or 2 dB.
Also note that if you are adjusting these setting with your voice, then the Air Talent comes in and uses it, the settings may not be appropriate with their voice. I gave the above guidelines to an engineer not long ago and came in the following day to his studio and found both hosts mic audio sounding horrible. One host was a woman and her voice was fighting with too aggressive of a gate, so her audio was very choppy. The male host was very good at projecting and actually was climping (gain too high). So make sure you test your settings with the actual people that will use the mic and try to get them to speak into the mic as if they were On Air. Don't just say hello, but actually have them read copy.
Good luck and happy audio.