Server Configuration & Management:
There are many things must be done to ensure that a website can work as it should:
Firstly, all the permissions of the files and folder must be set in a way that no one can alter them to create a back-door to the website.
Secondly, the access to the restricted files and folders must be checked. Just to show how important it is, I bring the example of a magazine which was supposed to allow only the subscribed and paid customers to download a new issue. But if you knew the address of the folder they put all the published issues, you could download them all without even signing in in the website. So everything must be double checked to make sure things work as they should work.
Thirdly, there are many settings that can be set properly to boost the website's speed and the response time.
Fourthly, when a website gets popular and more and more people visit it, it may happen that a shared hosting plan is not enough any more, and that would be the time to review all the hosting options and choose the most optimum one, based on the number of visitors and the services offered to them. A hosting can cost from a few dollars a month to tens of thousands of dollars a month. So it would be necessary to devise a roadmap along with the growth of the website's customer base.