Hey there

Firstly, learning the language is a good start. If you want to function well in the country you need a very good grasp of the language (both speaking and writing).

Secondly, getting a degree. Getting work in Japan, alot of employers and even the Immigration office would expect you to have a degree of some sort. If not, usually if you have many years experience in a similar job (say for example 7-10 years) is the alternative. What type of work you want in Japan is a bit harder to say. It's not easy getting particular jobs such as in the Medical/Health & Science related skills (it really depends! if you have a particular skill then better for you) but usually iv noticed that Business/Languages and English teaching are the safest bet.

Thirdly, visit Japan. Even if it's just a short trip. Experience the culture, people and society first hand before making any big decisions.