Hi Laura, I edit on Adobe Premiere Pro and I did find Adaptive Noise Reduction rubbish as it has a delay, there are other noise reduction plug-ins and a mixer in Premiere Pro that can help to a degree, but it all depends on how bad your sound is. If it’s really bad the only thing I can suggest is bring your actors in and record their dialogue again.
You don’t need a sound studio for this, use a quiet room away from traffic with your MIC plugged into the camera. Make sure the room is not too big, (a bedroom is good for this as things like beds and clothes sucks up unwanted sound), place your directional MIC and actors away from the windows, shut all doors in the room, turn everything off, computers, heaters, etc, and record. One tip is to record the bad sound on your cell, make them listen to it so they can get the inclination and timing. They listen, you stop the recording and you make them say it 5 seconds after they have heard it. Reason being is that they will retain the tempo more if there’s less of a gap between them hearing it and them recording it, all they have to do is copy what they’ve heard. I must admit there’s more to all of this than what I’ve written above but this is the basics.
When editing, if the scene is people talking to each other, if the new sound drifts off, cut to other actors who are listening, then back to the main person when the sound is back in sync. Also what helps the new sound work is room/outside atmos. This sound once placed over the new dialogue and mixed it should cover the mix of the new sound levels.
There’s a lot of atmos sounds for free on Youtube, also lots of sound effects too. As I said depending on how bad your sound is you might have to recreate the sound again from the floor up, this is a very cheap way of doing it.
Making films is about knowledge and common sense and sometimes you’ll find common sense is not too common.
I hope this helps.