How to Choose a Model Train
Space and Scale
You need to think about how much space you have for your model before you even think about getting one. This is because there is a scale associated with each model. The scale basically tells you the size of the train you are building. Majority of the train enthusiasts prefer the HO scale, because it takes less space but still give you a nice detail. However, if space is really a concern for you, then you should look at the N scale model. The bigger scale are the O scale, they are going to take up quite a bit of space but they give you really great detail.
Requirements
You can to set up your own model railroad, piece by piece or to buy a complete set. Generally speaking, a complete kit still lacks the model railroad setups like the scenery, but the advantage is that you can be up and running in a short time. Moreover, you still can add on to the kit easily by buying the parts you wish to add on later. Just remember that when you are buying the add on, you should be looking at things of the same scale.
Things to look out for
When you are buying a new model train, make sure it is DCC enabled. It is important that you have your train DCC enable so that you can run other trains at the same time with little difficulties. Of course, if you are just going to have one train then, this is not an issue, but you will never know whether you will be buying more trains in the future.
Finally, I do recommend you that you should visit your local model train store and have a chat with the staff there. People running this store generally passionate about model train and is very willing to answer to your question if you have any. Moreover, you can learn a lot from them by simply talking to them and asking them what they like.
Model train building is an exceptionally interesting hobby and I am sure that you will have hours of satisfaction by simply building and observing them.