All I drive is 10 speeds so my style might not work for what your driving but this is what I do and its good info. I watch the tach and the speedo.

For down shifting here is a speed chart

9th - 45mph
8th - 35mph
7th - 25mph
6th - 15mph
5th - 10 mph
4th - below 10mph, only need a small shot of fuel to get her to slide in

I remember these if I miss a gear down shifting or up shifting, lets say I had to stop really quick for what ever reason, car pulls in front or stops all of a sudden. To get going again I look at the speedo, move it in front of the gear I know it will go in, give it some fuel and she will slide in.

Stopping for red lights and general stopping I use the tach, If I skip down shift two gears, from 10th to 8th I let the rpm drop to about 900, give it fuel to around 1500 ( that depends on your truck) and she will go into 8th, or one gear I let it go to 1100-1200 rpm, shoot the fuel to 1500 and she will go to 9th for example.