Mikey -
Here's my advice based on flying FSX for a year and a half and 36 glorious minutes as pilot in command of a Cessna 172, LOL. Kim, Ken, Mike or other guys with some more water under their keel can chime in if I am wrong here...
As always Mike Gibbs is right on. Flying and trimming for a specific airspeed (even if it's not quite the right one) is the starting point. If your airspeed is constantly changing nothing will ever settle out for you.
Some other realizations I've had that have helped me:
1) Jetliners do not like to slow down and come down at the same time. If you want to slow down, the cost is some time in level flight to bleed off speed. Plan for that. Once you slow down to a desired speed you can then pitch down to descend at that speed. Planning is key though...get yourself slowed down and put out some flaps (~15 degrees) to fly level at ~200kts, 2500-3000 feet above the field well before you get to the ILS feather. Just before you get to where the glide slope intercepts your flight path, putting out your gear and approach flaps will get you descending at a lower speed probably without having to touch the throttle much.
2) If you have the field in sight, you should figure out the spot on the runway that doesn't appear to be moving This is the spot that you would hit if nothing changed! I generally try to make the two big solid white 'aiming points' on jet runways (1000' from the end I think) that unmoving spot...and then land just past them after flaring once I get there. Once you make this a habit you will find that your eye can be more sensitive to changes in glide path than the PAPI lights!
3) The ideal landing approach has you at a desired airspeed with flaps/gear out, descending somewhere between 500-750 fpm (faster if your approach speed is fast), with your nose near level, up or down a few degrees. If you are pitched up a lot to maintain that descent rate, your approach speed is probably too slow. If you are pitched down a lot you are probably too fast. The key as I said above is picking a speed and seeing how it works, adjusting power to change your descent rate. If you make your adjustments small the plane will have time to adjust and stay at the speed you are trimmed for. There is no law against practicing this at altitude; once you can set the plane up to descend at the speed and rate of your choosing, the landing itself is nothing!
4) Once you have a stabilized approach, the landing flare is just practice. I try to cross the threshold at about 50', then retard the throttle as I level off with the wheels just above the surface of the runway. Then I hold my pitch attitude (should only be a couple of degrees up) and let the airplane settle onto the runway. Be careful not to level off too high or you can build up to much of a descent rate and prang the runway. When your mains touch down deploy the spoilers (or better yet fly a plane with autospoilers and they will deploy for you) and gently but positively lower the nose. Once your nose wheel is down engage reverse thrust and brake as needed - shouldn't need much. Go to idle throttle again once you slow to 60KIAS.
Watch the FS "instant replays" of your landings to get feedback on your flare. Sometimes the difference between what you think happened and what it actually looked like are very different :) I just landed an Airbus A340-600 (longest airliner in the world)...looked great from the cockpit, but when I watched it from the outside I saw that the back of the plane barely cleared the trees and my mains touched down just past the numbers! Once you start flying the big iron I guess you need to account for that.
Good luck!
Matt
Matt Smith, WWA2218, CAT IV
Rio de Janeiro (SBGL) Hub
FSX Acceleration/Vista64