Build the suspension per instructions. Make sure everything lines up. And don't forget to put the poly-caps inside the drive sprockets! (OK, I admit I've done this.

Glue and paint the tracks off the vehicle. Don't try to shorten them or anything else -- they fit just fine right out of the box.
When you are ready to put the tracks on, simply remove the drive sprockets (with the poly caps, this is pretty easy), slip the tracks around the idler and bogeys. Before you have them completely fitted, fit the drive sprockets into the track and slip the drives onto the front axels -- the rest of the tracks should pop right into place.
If the tracks are a bit stiff and stand up too high from the bogey skid plates, add a spot of super glue to the top of each skid and glue them down.
I have been using this technique on Tamiya M4A3 suspensions (and many other manufacturers as well) since the Tamiya M4A3 was first released back in 84 or 85.
A couple more suggestions: Fruil makes a nice metal barrel for this kit that is a drop-fit. Eduard makes a "Zoom" set for Shermans that includes just the bare essentials -- headlight and taillight guards and a few other small parts. Well worth the money and a cheap way to dress up a kit.
Don't be surprised if the Sherman bugs bites after this build!
