As a new user, how should I decide to upvote and downvote questions, answers and comments?
It's great to welcome so many new users to this forum.
Many new users don't realize that voting activity is an important metric for this site as a whole and for the experts who volunteer their time and knowledge to answer questions. Don't be shy. Vote early, vote often!
Hope it helps.
Voting is vital for SE sites.
Voting incentives users to keep answering as the mined ethers incentives the miners to keep mining. Besides, it helps newcomers to spot easily the best answers.
I'd love to see someday stackexchange enabling voting even for non-logged in users as the vast majority in my opinion doesn't have an account in SE so they don't vote.
for me :
an upvote = thank you