What is the length and width of the tent? As a general rule mention, you have to anticipate the need for more space than you really need. It is better to spend the tent that gives you more space than saving a tent that will force everyone to spend the night cramped in a small space. You can find leading supplier of military tents over 30 years online.
How high should the tent? The same rule applies to the tent ceiling height – giving an allowance. The idea is to make sure that you can stand upright while inside the tent. If you get a tent that is so short that you have to crawl just to get inside, then expect to bump your head on something every time you get up in the morning.
However, you can only do this with a larger tent, such as military tents you can find in army surplus auction along with other camping equipment. If you plan on going for a smaller, simpler camping activities, then you can go to a smaller tent, but you still need to make sure that you have enough space to move.
Do tents provide enough space? In particular, you need to make sure that the tent can fit an inflatable mattress or sleeping bag when blown up or rolled out. If not, you'll be stuck with no source of comfort when you sleep in a tent.
Is the tent is too heavy? Make sure that the practical tent easy to carry around when it collapsed. Also, make sure that the tent is not easily carried by the wind. The tents are suddenly getting destroyed by the strong winds could easily collapse on you and camping equipment.