Any special tricks before you touch a shamisen that has been lying in a corner for “a few” years? This is the Beginner’s Shamisen I got almost 9 years ago - so a basic nagauta instrument.
Apparently I need new nylon and/or silk strings… And possibly some other upgrades from the shop ^^
That’s a complex question to answer without a photo, or fifteen.
Was it stored horizontally, inside a hard case, without the influence of high temperature and humidity variations? Was it stored assembled?
What is the current condition? Is there any mold, gunk, or heavy dust?
Is it a mitsuori (a Shamisen that disassembled in three parts)? do you notice anything missing?
How about the skin? Is it hibiki or leather? What is the condition of the skin and glue?
If you don’t have anything else apart from the Shamisen, you may need doukake, neo, strings, a bachi, yubikake, and maybe a fujaku.
The “trick” for me was reviewing courses in the schoolhouse. My ShamiBuddy needed the top skin repaired so touching it had to wait 
I spent the repair time reviewing Crash Course 1 & 2, Body Mechanics ( 
) and Proper Form ( 
). Revisiting the content helped me to “jump back in” once I got my SB back.