As shamisen is relatively obscure and shrouded in some degree of mystery, it's very easy for some folks to treat the shamisen as something more sacred than any other instrument, and thus push misconceptions based on what they don't know. Practically speaking, the shamisen is just like any other instrument. It has it's unique traits, but all instruments have their own unique traits. In an effort to lift the veil of mystery off of the shamisen, I strive to emphasize the practical (sometimes physics-based) reasons behind the elements of shamisen. For example, some folks have said, "You need a polishing cloth to play shamisen, because you must wipe your shamisen after every session otherwise you will ruin it!" In my opinion, such a statement is coming from a source of fear and ignorance, rather than understanding and experience. What's worse is that a newcomer, who has no experience to rely on, is likely to hear that and make decisions based on someone else's fear and ignorance. Because of that, I recommend being very careful of where you get your shamisen information, because in my estimation, over 85% of people really don't know the reason behind elements of shamisen yet will speak like they do.
So the way I recommend items is just like my response to the statement of "You need a polishing cloth to play shamisen, because you must wipe your shamisen after every session otherwise you will ruin it!". Practically speaking, you don't "need" a polishing cloth to play shamisen. It is good to have for long-term care, but because your shamisen will still make sound without the presence of a polishing cloth, I don't consider that as something "needed to play".
And with that, the following list of recommended items are sorted from "essential" (in the sense of "your shamisen will not make sound without it") to "it's good to have" (in the sense of "it's not required to play, but you might see benefit to having it").