I let the film soak for a few minutes before working. Then hold the film down to the bottom of the tray with two fingers and wipe across the film with the Q-Tip. Pretend you are painting the film so you cover the whole surface evenly. Use light pressure but firm enough to "scrub" away embedded dust.
Make sure you hold the film and the Q-Tip completely under water. Rotate the swab as you move so only clean cotton touches the film. Change to a new, clean swab often. Any tiny, little bit of grit on the swab will scratch the film. What's worse, you might not know that you scratched the film until you put it back in the enlarger and try to print from it.
Do both sides of the film. Swirl the solution a couple of times to wash away any loose particles then hang to dry.
Wait a minute or two so the film can drain. Shine a light off the film so you can see the reflection. You should be able to see any particles still adhering to the film. If there are still particles, wash again or, better yet, use a syringe filled with your solution to squirt the dust off the film.
I just washed this negative that way: http://www.flickr.com/photos/randystankey/5875851924
With a picture that dark (or a negative that clear) I thought I would never get it clean but I only had to dab out two or thee small spots on the final print. (The one and only thing I like about digital/hybrid photography is that spots are so much easier to clean up.)
In the future, I think I'm going to get an electrostatic air cleaner if I can find one. Combine that with keeping the darkroom clean and I think I'll be able to keep the dust down to a tolerable level.