Start at the beginning with simple training clothes. Long jogging pants and a sweatshirt in dark colors are sufficient. The use of well-known suits of Japanese martial arts (karate, judo, aikido) is allright. You are holding your wooden sword left on the side. The next step should be to buy a belt for correct location of the sword.
An Iaido Belt (Obi) is much broader, longer (about 4 m) and thinner than a normal Budo belt that you receive in the store. Thus he can be wound in several flexible layers around the hip. So he always sits in the same place. Because of the width there is a tight fit of the sword. The abdomen (Hara) is easily fixed in the Obi. At the same time this supports both the upright posture.
The question of buying a Hakama, the wide trousers, follows quickly. Again here are a few extras to consider. The Hakamas cut allows to make big movements with. We bear this in traditional black color. Actually, all traded hakamas are suitable. Kendo-Hakamas are a little too bulky, because they are made of thick cotton cloth. Iaido Hakama are made of polyester fabric. This material is because of its durability best suitable. On special showings (Enbu) Hakamas with some percentage of woolen or costly silk materials are worn.
A special jacket is worn with Hakama, the Iaidogi. It has a unique cut. It is longer than, for example, karate jackets, so that the lateral sections of the Hakama are covered. An Iaidogi is made of relatively thin material like a hakama. A jacket is offered in two fabric types: polyester or cotton. If this is made of polyester, one will wear below a light cotton gi (Hadagi) out of hygienic reasons. A jacket made of 100% cotton can be worn without a hadagi; this is practically.
As a beginner, take a wooden sword (Bokken) for practice. It does not cost much (about 15 €). The kata exercise is facilitated. The weight is quite low. So you moves easily to get used with a sword. Even in pair exercises a Bokken is very useful. Thats why you need it again and again, even if you already should possess an iaito. Unfortunatelly the most Bokken are manufactured out of Mahogany-wood.
Soon one would practise with an Iaito (replica sword). This is like a real, sharp samurai sword. The blade consists of an alloy die casting with chrome finish. It is usally dull but can be ordered semisharp too. Weight, style and design of the handle are compa rable, the balance less. The wooden sword scabbard (Saya) is sometimes genuine.
Prices vary depending on length of the sword and processing of the blade. Cost drivers are decorationon handle, tsuba and scabbard (Saya). The sword prices ranges from 250 to 1000 Euro. They depend on the length of the swords and the scale of individual desires. Buying a second hand sword makes sense on the beginning. Then later one can choose individually a new sword.
An Iaito is more ambitious to use. Saya and blade must moved synchronously. The blade is heavier, the weights are centered. These are significant differences compared to the training with a bokken. All the movements are necessarily subtle and complex. Errors in the movement are clearly visible and noticeable (and audible too: the sound of cutting shows much about the quality of movement).
For cleaning and maintenance of Iaitos you need a light oil. Ideal is Balistol weapon oil. This product does not pentrate the chromium coating of the Iaito blade. Therefore it remains intact. This agent cleans the blade, greases it for the next mission and spreads a pleasant scent. The care is also skin friendly. For cleaning you keep two small (microfibre) lobules ready. With the first one cleans the blade after training. With the second you apply some fresh weapon oil later.
A high quality sword bag is essential for the transport of sword and bokken. There simple bags from imitation leather. These hold about 3-5 years and then get cracking. Even better are bags made of genuine leather, because they are smoother. Small side compartments are good for cleaning adds. A large version of the sword bag — eventually with divisions inside — allows simultaneous transport of sword and Bokken. So you should ensure to purchase good quality.
Who is training much Iaido, should buy a pair of knee pads. Nobody can move on hard (parquet) floor so good, that he is in need of some cushion for repeated practice of sitting kata. Very useful are kneepads with neoprene filling. Simple quilted protectors suck, because they can quickly bruised.
So called Zori, japanese rice straw sandals or flip-flops are in Training and so on practical for quick in and out. The dojo is barefoot zone — outside of the training area, so the dojo, one always wears shoes.