
You need to switch to Firefox to use this add-on. It works seamlessly both with the regular and developer edition of the browser. Some Firefox users find it a bit confusing in the beginning but it's not at all.
As I said before, divide your browsing activities into few major categories and according create containers for the same. It'll keep your category-related browsing activity isolated from other sessions.
To get started, first of all, install the Multi-Account Containers extension on your Firefox installation. Thereafter, go to the add-on settings by clicking the Add-ons and themes option within the menu.

Here, activate the Enable Bookmark Menus options. It'll facilitate the opening of bookmarked URLs in your desired container.
Optionally, you can also enable the Tab Behaviour option. But, I never use this option as I always want a new tab for a container.
Once you've configured the basic options, it's time to create our custom containers as per our needs. For that, one must plan and choose appropriate names for the group of containers you're going to use. This way, you can easily assign the different categories of URLs to the container group of your choice.

To do so, click the Manage Containers option to start the container creation process. In the screenshot, you can see 4 different container categories.
The container management screen is as follows. Feel free to give your meaningful names to your containers.

Click the New Container button to customize your new container.

You can give a name of your choice to the container, can assign a color to it, and can also assign an icon to it. This way, you can personalize the container attributes as per your preferences.
You can create as many containers as you want, though I'll recommend creating a handful number of categories for your group of websites falling under each container.
Adding a website to a specific container is quite simple. Here's how to do it.

Open the website in a new tab and click the icon in the address bar as shown in the image above. Select the container you want to assign to it.

Selecting an option from the drop-down will open the website in a new tab associated with that container. Next time, whenever you'll open that website, it'll ask for a confirmation if you want to open it in the previously selected container by default.

Make sure to select the checkbox to ensure your website is always opened in that container in your future browsing sessions. Whenever a website opens in a specific container, its icon is displayed in the address bar and the tab itself gets a top border color associated with that container.

From now on, whenever you'll open that specific website, it'll always open in that container. And, trackers and analytics scripts from websites residing in other containers will never know anything about your web activity in this container.
Essentially, you create an isolated web browsing space within the web browser to keep your activity private from other tabs.
In case, you want to remove a website from a specific container, click the add-on icon and thereafter click the arrow sign on the right side of the container where you added that website.

Thereafter, hover on the website entry and click the cross icon on the right side. This action will remove the website from that container and any future access to that website will open it in a normal browser tab. You can again add it to a different container if you want to do so.

It's one of the must-have add-ons I use and highly recommend to you too. One of the best uses of this add-on is to use multiple accounts of the web services which generally allow one login at a time
Do try it once and tell us your experience with it.