The sort of fishing you want to do will dictate the rod length and rating to a large degree. Read the sections on the main styles of fishing if you are not sure. Then you are ready to start looking more closely at rods.
You find that many rods have multiple ratings e.g. 5/6 or 6/7. Some have an even wider range. If you are starting out we recommend you go by the higher rating. As a rough rule of thumb the higher rating is applicable to weight forward lines and the lower rating to double taper lines.

Rods are made of a wide range of materials but graphite is the most common these days and offers good performance at a reasonable price.
How much the rod weights is one factor to look at. Generally speaking the lighter the better since this makes casting easier and makes a big difference especially if you are casting all day. Graphite rods offer low weight with good rod strength compared to say fibreglass or cane. However, the lighter the rod either the more likely it is to break or more it will cost.

The number of rod pieces is also a big consideration. These days we have to travel further and further to get good fishing so a compact rod is very convenient. Consider a 2-piece 9 ½ ft rod. This will take up over 5 ft of length and would be difficult to fit in any car boot. Some airlines now charge extra for carrying rods of this size. Even a 3-piece 9½ ft rod will be around 3½ ft in length. OK for the car boot but still wont fit in most suitcases let alone aircraft hand luggage.
However, more pieces means a heavier rod and higher cost. But these days, manufacturers are turning out great quality multi-piece rods at affordable prices. A 5-piece rod like the Redington Wayfarer packs down to just 24 inches and will fit into most suitcases and you should be able to take it on an aircraft as hand luggage. The Cortland CL 6-piece rod is even smaller.
If you expect to travel to go fishing and can afford it try to get at least a 4-piece rod. Otherwise, a 2-piece is fine but be aware of the limitations.

The rod "action" describes the shape of the rod when it is loaded. There is an awful lot said about rod actions and a lot of physics behind it that we have no wish to go into. Suffice to say that for the beginner we recommend a rod that bends further down the rod the more it is loaded - this is often known as a progressive action. Beyond that, it is largely up to personal preference and casting style so we strongly recommend you try a rod before you buy it. Come to our shop or arrange for a trial on one of our local trips. If you are a beginner you should at least have some casting lessons first. You could even consider borrowing some tackle until you pick up the basic skills. This will help you make a more informed choice of rod.

Most rods come with a carry tube these days. These are essential if travelling by air and very useful even if not. Dropping things onto rods or knocking them against walls, cars, the ground etc will weaken the rod and it may break unexpectedly whilst fishing. So ask whether your rod comes with a carry tube.

Many rods now come with a manufacturers warranty which these days can be as much as 25 years or even "original owners lifetime". Some are even unconditional which means that the rod is repaired or replaced no matter what caused the breakage. Now we all know that you don't get something for nothing but its nice to know that if you break a rod early on then you are not up for a big outlay to replace it. So think of it more like insurance.
On the other hand, if you are in the wilderness and break your rod you still can't fish no matter what the warranty. If you are on an O'Reillys fishing trip we always have spare rods we can loan you in case something happens to your own.
Remember also that, with care, a rod can last you a lifetime. But we all find that as we get more experienced we need more specialised rods or different actions, or improvements in technology convince us that the latest equipment will make fishing more enjoyable. Take this into account when comparing warranties for value for money.