Quick Sound Design Question and Tip – low dialog sound levels

I’ve been running into this a bit while cutting footage for my very first production, which was the 42-min pilot for my web series, 7 Shades of Lenity.
I found that some of the dialog was recorded too low, so I have to crank the gain on the tracks, which also increases the noise level (hiss, white noise, background noises), and only goes up 6db max, which isn’t always loud enough.
One trick I found, is to double or triple (or more) the dialog tracks (kind of like a choir is louder than a single voice), but even that has limitations, and I’ve had to raise the gain even so.
Obviously, raising the gain a little in each track (to me), sounds better than raising the gain a lot on a single track.
Does anyone have any experience with this that they’d like to share?
Also, does anyone know of any plugins to lower or eliminate the background hiss/white noise. An EQ trick maybe?
The only EQ trick I know would be to analyze the track and figure out what the noise frequency is, and lower or remove those frequencies from the mix — you might get rid of some voice frequencies too, so it may be a job of trial and error, tweaking the frequencies.

Val Gameiro
Writer, Director, Filmmaker