You may or may not want to have comments on your site. But if you have comments your site will be spammed. It then becomes a case of how well you deal with the spam.
To minimise comment spam and other types of spam, make sure you've installed the Cloudflare plugin mentioned on my WordPress plugin recommendations page.
In the case where I allow comments, I prefer to set all comments to manual approval. However this will turn into a lot of work if your site receives large numbers of comments.
I think comments are less expected than they used to be in the past, and really are just an invitation to spam. Overall, my advice would be to switch them off altogether.
Go To Dashboard → Settings → Discussion.
If you are allowing comments, make sure one of the following options is checked. If you end up getting a lot of comments this setting will be a lot of work though.
The other options on this page are up to you. However if you have disallowed comment the remaining options are not applicable and you can ignore them.