And yes, the problem I see the most in new pilots is a fear of being too fast, and then being rushed into the approach. They tend to over-correct for that, and want to slow down to, say 220 knots at 20 miles or more. Now this is much closer to an efficient glide speed (green dot) than 250 knots is, at 220 knots the aircraft isn't washing off energy in parasite drag the way it would be at 250 knots ...so the aircraft drifts high on the approach path. Now the pilot has TWO problems to deal with - getting back onto the approach path AND dealing with their excess energy.
If you remember nothing else (other than your 3x table), remember this, which is fantastic advice. Keep the aircraft at 250/240kts until 15-17 miles and you will be a good place. Not least as this is what the aircraft would do itself if it flew fully managed, and is what the descent profile is based on.
As ever your company manuals and the FCTM should be a good guide too.