There are no real specific mountaineering clothes; there are no guidelines, as to what you should wear, and what you should not. In many cases, common sense should prevail, as to what clothing should be worn. However, there are a number of items of clothing that are not exactly essentials, but, they are very often used, and most mountaineers, beginners and more advanced will prefer to use them.
Depending on where and when you are doing your mountaineering, different clothes will be needed. For example, deep in the Himalayas, you will need coats; hats etc. and you will most likely also need either a guide, or some sort of satellite navigation system. Although; either previous experience of the area, or a guide would be the best and safest option. There is no substitute for experience in a dangerous sport like this.
On the other hand, if you are in a low mountain range close to the equator, for example in Kenya, then cold weather clothes will not be necessary during the day, but, they will be needed at night time. Places like this are notorious for this type of weather system. In this case, you would therefore have to pack a wide range of mountaineering clothes, covering warm weather and cold weather clothing, so that you will not be caught out. One of the most important aspects of this sport is being prepared. You must be prepared for all types of weather, and scenarios. Therefore, a wide range of clothing must be packed.
To conclude, you will most certainly need a good set of boots. These will need to be very comfortable, as you will be hiking for hours on end. If tackling some of the highest mountains, you will need crampons, and an ice axe. These can also be purchased from specialist stores, on the links on this page. Coats, hats and gloves will also be a necessity. It has now become quite common to take under armour. This can be used to either keep you warm, or also keep you cool, depending on the type you buy. These can be a very useful addition to your mountaineering clothes, and will definitely help keep you at the right body temperature, all day long.