new to asa 5505 need help

hey ASA gurus,
I have my ASA 5505 RUNNING good but my problem is how to stealth (or can I?)
ports that I used and are open?

I use ports:

22 sftp server
444 https for my www
443 owa from exchange
25 SMTP exchange server

is there some way to lock down? I have static routes to their servers. and ACLs working
they work good just want to make sure all is locked down good.
thanks