I'm working on a website which is already up and running, but it needs a redesign and a lot of fixes.
I don't want to take the site down, because I still want customers to have access to the site, but I'd like to build on the new site alongside this one, to be able to test the site online with access to the same databases, and then eventually replace the website seamlessly.
What are the recommended steps to doing this? I don't want to just wing it and make a mess.
I'm new to web development and I've never done this before for a running business, so I'm just unsure of the logistics involved.
Thanks in advance!