devanshj,
Welcome to the forum! We used to make solid wood tanks when we were kids. Like everybody else said, get some reference material for scale and go from there. We used to make the upper and lower hulls, turrets and tracks (we didn't do individual road wheels), all cut to shape, then detailed. This would mean adding hatches, fenders, exhaust pipes and such to the hull; hatches and main guns to the turret. We used what ever we could find from old tin toothpaste tubes, now they're plastic, to nails, wire, string, screen, card board or what ever to detail the tanks.
Mine always looked like wood with a bunch of garbage added to it, but my brother and his friend made some really nice Tigers. It was a lot of fun.
Ron