Before stepping inside a kendo store, you should get permission from your sensei. Do not buy anything unless your sensei allows you too. Not only is it disrespectful, but you may not be advanced enough to buy anything.

If you are buying your first bogu or first hakama and kendogi it is recommended that you not buy online. Instead, you should go to an actual store and get measured. Nothing is worse than accidentally buying a hakama that ends at your feet, or a bogu that you can't fit into.

If you are still in the process of growing you should get measured each time you buy a bogu or hakama. You shouldn't spend too much money on a hakama, since you will most likely grow out of it in a short while.

With bogu you have a bit more latitude with sizes. However, it is suggested that you not spend too much money on your bogu either.

If you are an active participant in tournaments, you should buy two pairs of bogu; one for practice and one for tournaments. The one used for tournaments should be kept clean and attractive as it is a common belief that the better you look, the more chance you have of being awarded a point.

http://www.international-kendo.com is an up and coming kendo site with a wealth of information.