I think the biggest helper I use is a screen frame in the bathtub. It fits down in securely, and had kind of a heavy gauge window screen on it. The cats can claw into it, while being bathed, and are not in standing water which most really hate.
I use an old Wonderwate rake, with the rounded tips, and split out and rake a section at a time. Some cats do better if you do, say 1/4 at a time, put them back, and do a something else, and come back to them. Most I find are not truly bad, they just can't tolerate pulling for extended periods..they will do better with breaks.
Cornstarch works really well worked into a matted area that you don't want to clip.
On really, really matted tummies, I put a thick glob of Vaseline on the nipples, as they are so tiny they can be cut really easily. The Vaseline can be felt on the clippers when you hit it, and wipes off easily.
If you have an old stuffed toy, keep it handy, as many cats will grab and bite it very aggressively, when it hurts or pulls.(Better the toy than you, right?) I just put it in front of the cat, while working on him, and you would be surprised how many attack it when they get upset. Maybe they think that it is OK as long as they attack something, anything!
On stud tail, I pack in boric acid powder, while doing the combout, prior to the bath. It absorbs most of the oil there. If you scrub the area, it will stimulate more oil production, and compound the problem. It doesn't hurt to have a catnip toy around, some cats get really 'drugged out' and it can relax and calm down some pretty well.
On Persian faces, which depending on the extremity of the nose, are usually dirty. I wipe it all down with a wet washcloth first, while I begin bathing the rest of the cat. This give the nasties a few minutes to be softened by the water. Then using a Q-tip, and a SOFT toothbrush, I scrub the 'gutters' on each side of the nose. Be very gentle, because those eye drainage 'gutters' can get very crusty and it seems to attach to the skin. Be careful, or you will remove fur as well as scuzz. You can use a flea comb on cheeks, to pull it off, after it has softened. Check the chin, as many Persians suffer from feline acne (little black dots...suggest to the owners they switch from plastic food dishes, and use glass, ceramic, or stainless steel)
Do not trim feathers on the feet, but DO comb them out, as the ball up and sometimes even hold bits of kitty litter, etc. Wipe out ears with alcohol on a cotton ball, most ear cleaners leave the surrounding fine hair greasy or oily.
Towel the cat really well, and cage dry on low-med for a while, but remove and hand dry the finish..against the way the hair lies. The idea is a very short coupled, cobby, rounded cat. You should see no flat planes, or sharp angles. The cat should look like a several spheres..head, body, etc.
Trim the tufts on the ear tips, to make the ears appear smaller, and more rounded. (Some pet owners like the tufts, so check first) If there is excessive (breaking a smooth, rounded span between the ears) feathering on the top skull, with thinning shears (little ones) blend the 'horns' between the ears to blend in with the shorter length of fur on the top skull.
Excessive mutton chops on the cheeks should also be blended, to give a rounded appearance, (It is easier to visualize a softball with fur on it, for the head... anything that detracts from that should be thinned, trimmed, or plucked away, but you should NEVER see scissor marks)
On the tail..it should appear very short, just barely reaching to the
shoulder when brought around to the side. After bath and brush out/blow
dry comb the tail hair towards the tip, and grasp the tail tip in your
fist. Gentle pinch/pluck the long straggelies, so that you end up with a
shorter, ROUNDED tail tip.