Default WP .htacess code

# BEGIN WordPress

RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

# END WordPress

expires headers

<FilesMatch "(?i)^.*\.(ico|flv|jpg|jpeg|png|gif|js|css|woff)$">
ExpiresActive On
ExpiresDefault A2592000
</FilesMatch>

If we need to set a separate Expire Headers rule for each of your filetypes we can use this snippet

ExpiresByType image/png A2592000
ExpiresByType image/gif A2592000
ExpiresByType image/jpg A2592000
ExpiresByType image/jpeg A2592000
ExpiresByType text/javascript A2592000
ExpiresByType application/x-javascript A2592000
ExpiresByType text/css A2592000