difference between not to + verb VS to not + verb

difference between not to + verb VS to not + verb

(any difference, in term of both meaning and usage, between the following 2 sentences?

I decide to not visit Japan.

I decide not to visit Japan.)

•  I like the second one best. It is by far the most ordinary way to express the idea. The first one is not incorrect, however.

• The natural version is "... not to visit Japan."
  
  The "... to not visit Japan" version is also used, thought likely to be considered casual and not recommended for formal writing or examinations unless you are very sure it would be accepted.

(What's the correct form of this?

I've decided not to take more medicine 

or

I've decided to not take more medicine.)

• I would agree that the first sentence is probably correct but it would read better as "I've decided not to take any more medicine"
  hope that helps

• However, it is common to hear the second sentence in general conversation - unfortunately, many people rarely adhere to correct grammatical convention in everyday speech.

• People get their-selves in a right old state about splitting infinitives and it has become a nitpickers' charter. In normal, every day language "not to take" and "to not take" are both valid. 
  
  I'd probably say: "I've decided to not take medicine any more / I've decided to drop medicine".

• It doesn't matter.
  
  Several centuries ago people started trying to apply the rules of Latin to English. In Latin it's not possible to split an infinitive, so the purists of the day insisted that "You can't split infinitives!"
  
  Generations of schoolchildren have had it hammered into their heads that the particle to and the infinitive cannot be separated at all.
  
  It's simply not true, and people are starting to wake up to the realities of it.
  
  So you can say "I have decided not to ... " just as readily as "I have decided to not ..."
  
  Stylistically, the second probably comes across as 'better', but I think that this is because generations of educated writers have used this form, so it's associated with good writing, whereas the other structure was more common among sloppier writers.
  
  It's a shame that the rules created artificially (and incorrectly) by zealots of the seventeenth century are still causing people to worry today, as is evidenced by the first response here citing a "split infinitive". Infinitives can be split in English; they can't in Latin. English ≠ Latin.

• My take on this is that "things that need not be remembered" are things it isn't necessary to remember. "Things that need not to be remembered", however, are things that, for some reason, must be forgotten.