best way to secure cpanel and phpMyAdmin against hacks

I'm sure there's no foolproof way to guard against php injections and the like but my oscommerce store gets a lot of traffic and i'm getting concerned about security. currently it's on a shared linux host. i'm thinking i should move it to a dedicated or vps - cost is a concern so vps would probably be the best solution - i just want to make sure the upgrade makes sense - i.e. is there a better way to secure cpanel/phpMyAdmin  - i know about ssl, .htaccess and redirecting the nonsecure url to the secure url - but is there anything else i should think about before making the change? all of the stuff i just described can already be done on my shared server. please advise -thanks!