There are two ways to trim, well at least two ways that I use, I'm sure there are many more.
The first requires a bit of a hair stylist eye. I call it "point cutting" which is the term that describes using just the point of your scissors to cut, so as not to produce a blunt line. Take your scissors and point them towards the head of your bird. Gently move in and out, going closer to the head, and backing out and gently snip here and there to "thin" and shape the top knot. I use this the most with my show birds.
The other way is to gently pluck the small feathers around the top of the eye. You have to go slowly, and gently because the skin there is rather sensitive. I like to use tweezer and get as close to the bast of the feather as possible, if and when I have to pluck. You just grab the base of a single feather, give it a slight tug and it should come out rather easily.
ETA: If you dont want to trim/pluck, and dont want to give your bird a full bath to get her clean, get a box of baby wipes. Use them to wipe down dirty feathers, allow to dry, and brush it out.
