It's better not to add noise, it's kinda of a cheap feature, just like the subdivide tool; a shortcut that doesn't do the job properly, but quickly. Using either will still require a lot of manual tweaking to make it look nice/right.
I find it better to just do it manually from the beginning, it takes a little more time, but this is practical project just like any other art and design, so it's a given. Anyway, tweaking manually allows you to stick to the grid so that things never get so complicated you can't work your way back if you feel the need to. You just gotta get used to displacing faces on all 3 axis, also try reducing the affect radius (green wireframe ball) to 1 for precise manipulation and keep the manipulation strength to 2, 4, 8 etc to keep adjustments aligned to the Hammer grid along with the standard geometry.