I. Romanization = Spelling Japanese words 

I want to start with the Basics. And romanization of Japanese words is very basic, yet I often see mistakes by Japanese people writing English. 

There are two romanization systems commonly used today: Hepburn (ヘボン式) and Kunrei (訓令式). 

You should be aware of the differences and be careful which system you use when you write Japanese words in English. 

Hepburn is by far the most common system. JR train stations, Japanese passports, Japanese-English dictionaries, and English newspapers all use the Hepburn system. I strongly recommend the Hepburn system for normal writing in English. Kunrei is found most often in Japanese textbooks for foreigners and it is useful because it makes it easier to see the linguistic inflections. 

Notice the difference between Hepburn (left column) and Kunrei (right column): 

Shiga-ken | Siga-ken 
Chikubushima | Tikubusima 竹生島 
Kusatsu-shi | Kusatu-si 草津市 
Shigaraki | Sigaraki 信楽 
Takashima | Takasima 高島 
Hachiman | Hatiman 八幡 
Chomeiji | Tyomeizi 長命寺 
Aisho-cho | Aisyo-tyo 愛荘町 
Azuchi-cho | Azuti-tyo 安土町 | 
Takatsuki-cho | Takatuki-tyo 高月町 
Eigenji | Eigenzi 永源寺 
Ishibe-juku | Isibe-zyuku 石部宿 
Hokkoku Jinja | Hokkoku Jinzya 豊国神社 
Taga Taisha | Taga Taisya 多賀大社 
Hifuri Matsuri | Hihuri Maturi 火ふり祭 

As you can see, the spelling can be very different (especially Chomeiji). Many Japanese people confuse or mix the two systems. They might spell Aisho-tyo or Aisyo-cho. One reason is that many people type romaji with a personal computer and Kunrei system is sometimes shorter and faster to type. Kunrei is okay when you write in Japanese with a PC. But not good when you write in English in most cases. 

So please be more careful when you spell Japanese words in English.