The Floor : Yup, many types of tents come complete with floors, hard fabric that is sewn to the walls completely covering the ground below. If you read the aforementioned “water seeing up from the ground” line, you will understand that in a rainstorm having a cover over your head is not enough to keep the water from getting in.
Also in cold conditions, the ground can harden, making it far less comfortable even if you're in a sleeping bag. So if you are going to get a small tent with no floor, be sure to get waterproof blankets to cover the ground just in case.
The Right Size : Seems practical enough, but it can be harder than you think if you do not account for all the equipment you want to store inside, away from the elements. Not to mention how many people you usually take on your camping trips.
So the first thing is to quickly assess all the people & gear you take along with you; then check out the different sizes of tents. When in doubt, you'll probably want to go up a size to avoid everyone getting all cramped up inside.
If it's just one or two people, including you, a small dome tent should do. A larger number of folks will need a Wall or other type of larger tent.
Easy Set-Up : You have probably seen a movie where a clumsy fellow tries desperately to set his overly complicated tent up only to have it crash down time after time. That is not just a comedy bit, it happens quite frequently to those who choose tents that are more difficult to set up than they are willing to tackle.
Generally speaking, the dome and A-frame tents are reliably easy to set up, especially if you arrive after dark or may have to set up in windy conditions. A cabin-type tent is not so easy to set up; so be sure to familiarize yourself with the different types of tents and how they are to set up.
Time of Year : Do you like to camp mostly in the summer or is anytime of the year fine for you? This is an appropriate question because there are different types of tents made for specific times of the year. Let's face it; If your camping is strictly limited to the summer, then a lightweight tent is perfect especially out by the lake.
Generally speaking, the two most common types for most year-round use are 3-season and 4-season tents.
The 3-season is generally made for Spring / Summer / Fall, more moderate weather conditions in which the tent does “breath” more. A 4-season tent can be used all year round and is designed to handle the harshest winter conditions.