Create one .htaccess for each folder and make the permissions accordingly.
There are among quite vulnerable files :
./wp-admin/install.php
./wp-config.php
./readme.html
These are risky as if the server is updating their softwares (or rather PHP is not running), these files can be read on browser like text files.
Protect with these at .htaccess of the root :
# prevent browsing of readme file
<files readme.html>
order allow,deny
deny from all
</files>
# prevent editing htacess itself
<Files .htaccess>
order allow,deny
deny from all
</Files>
# prevent viewing of install file
<files install.php>
order allow,deny
deny from all
</files>
In wp-admin, the .htaccess must have these :
<FilesMatch “^(install\.php|example\.php|example2\.php|example3\.php)”>
Order allow,deny
Deny from all
#Allow from 88.77.66.55
</FilesMatch>
There is a naughty trick to prevent login – simply rename wp-login.php from FTP when you need not to login. After login, again rename it (unless you are logging out, this file is not needed). You can read the article of perishablepress.com for more tricks.
# is used for commenting out (the code will not work) in .htaccess.