Solo Travels to Tokyo

Hiya! I’m planning on going to Tokyo for 10 days at the end of the year in maybe the end of November / beginning of December range to give me time to save enough money and renew my passport (oops), but I am looking for ideas on places to stay that’s the cheapest but safest. I am looking into Air BNB, hostels or hotels. Which is best/cheapest/safest out of those three? Second, I’ll be alone, so I’m wondering what the best things to do are that don’t cost me a lot of money (also what did you do for money usage, like did you use debit or cash/what’s best?) and how far would you think is best to travel outside of Tokyo etc. I want to get the most out of the ten days, but it’s my first solo trip I won’t be traveling to see anyone for. Obviously I’m nervous/scared, but excited. Third, best options on buying the tickets. Would you recommend one round trip ticket or separate to and from tickets? I’ll be having to travel from Idaho to Seattle also, so I have more than the tickets to Japan, so any options in saving costs would be best. So, like what day to buy it on, etc.

Any and all advice would be best! Weather tips would be great too. :)

TIA ❤️