Adjust/check valve clearance.
Change oil.
You already asked about gear oil.
Clean/replace air filter.
Check battery and connections.
*Inspect and measure CVT belt* This is a little involved so you need to watch some youtube videos about this, do some searches and reading of the THOUSAND posts on here and the ask questions when done or in a coma, whichever happens first!
Get/download/buy a service manual.