What 3d program are you using? I do 99% of my modeling in sketchup, and I've modeled a rough T-34 before.
My workflow would be:
Set up all the views in their correct orientation and to the same scale - proper scale isn't important unless I know the size of some parts that I know exist but aren't shown in the drawings (bolts, gun bore). Make the views a group and lock them.
Trace the profile of the hull in the side view. Once I've got a good face generated, pull it out an arbitrary distance and make it a component.
Flip it and stack it back-to-back with the other one, so I've got 2 halves of the tank to work on.
Continue adding detail and making fixes from other views from there. In Sketchup specifically, it's important to group distinct pieces of geometry (hull, turret), but make components out of repeated geometry (track-links if you're going for that detail, wheels, bolts). You can't go wrong making *everything* a component, but you can making a group then copying it before you make it a component.
SpottedKitty wrote:FWIW, this looks interesting; there are a lot of tank models around, for sale or free, but I don't think I've seen many T-34s. Maybe I'm just not looking in the right places, it is a pretty iconic WW2 tank.
World of Tanks has a model of the T-34 in it. If you're looking in the right places you can probably either find an extractor or find an already extracted version.
Here's one I found in the warehouse for free.