I joined a new site, and realized there's no easy way to "browse" the tags page from the Ask a Question page. The usual tag select box has its useful autocomplete, but it requires me to enter something before I can see anything. It's my first time on that site, and even a link to the tags page would help. (The links on the right panel were helpful.)
It's easy! Just click the blue help icon at the bottom right:
and click on "Use existing popular tags". It'll take you straight to the Tag page.
Credit to @user289905: Alternatively, go here:
and click on "Tags".
Also, if you have the keyboard shortcuts script enabled in your preferences, you can use Shift + ?, G for "go to", and then click T to go to the Tags page. My favorite method.