Well, having a billing system if you have less than 5 clients isnt helpful as you can do manual billing as well. But a helpdesk is SURELY needed(Like osticket, cerberus helpdesk etc.)

The website needs to be professional and eye catching. You must be on a speedy server as well. Think what the visitors will assume when they would see your site loading in few mins? That surely annoys everyone, not just the potential buyers.

ALso, DO NOT OVERSELL. Never do this, as it'll bring more customers but when they'll go, you'll see them going away with lots of negative feedbacks about your company. So, thats definitely not what we need for a newly started company. Isnt it?