If the website requires a login for both regular activities and admins, e.g. a forum, I'd use separate logins which use the same user database. This ensures that XSRF and session-stealing won't allow the attacker to access administrative areas.
Additionally, if the admin section is in a separate subdirectory, securing that one with the webserver's authentication (.htaccess in Apache for example) might be a good idea - then someone needs both that password and the user password.
Obscuring the admin path yields almost no security gain - if someone knows valid login data he's most likely also able to find out the path of the admin tool since he either phished it or keylogged you or got it via social engineering (which would probably reveal the path, too).
A brute-force protection like blocking the user's IP after 3 failed logins or requiring a CAPTCHA after a failed login (not for the first login as that's just extremely annoying for legit users) might also be useful.