Okay, so as many of you might know, I'm a bit of an aspiring voice actor. I'm trying to get an acting position in the main game (as SCP-860-2 or something else along those lines), and I've already signed on for the mod Half Life: Resonance Cascade. As well as a few other mods not mentioned in the forum, but that's beside the point.

I recently downloaded Audacity to be a little more "professional." However, whenever I record lines, they always come out too soft. Then, when I go to apply filters, the result can often induce earaches. Is there a way for me to amplify my microphone in such a way that my input voice comes out loud and clear, instead of having to amplify it afterwards, where background noise becomes a major issue?

Furthermore, I'm having trouble applying the proper radio effects. None of the tutorials I have come across result in a radio effect similar to the Half Life HECU soldiers. Any input?

You can amplify the audio and use the "Noise Removal" tool. Just select a sample of the background noise, do "Get Noise Profile", then select the whole track, and then click 'OK' at the bottom. That usually works, otherwise, I can only suggest playing around with your mic a bit more.

As for radio effects, I suggest you play around with High Pass and Low Pass filters a bit, and combine them.