By default, the view in Microsoft Teams is as below (example)

But there are little changes that you can make to improve and optimize you experience in teams by changing the view and changing how things operate.

Change the way teams are displayed 

You can change the default view of your teams from the Grid view to the list view this will show all your teams and the channels below each of them, without having to open each team.

First go into settings to do this Click on the three dots and the top next to your avatar and click settings (as shown below)

Then go to  Appearance and accessibility 

and change the layout from Grid to List (there is no save it auto saves this change).

If you now, click back on Teams on the left you will now get your teams listed with the channels below each one (example below) 

You Can drag and reorder your teams in this view too.

Chage how Files are opened 

By default, the Teams app opens files such as word Documents and Excel Spreadsheets within itself using the the web version of each.  You can change this behavior to open the files into the desktop application instead. 

To do this go back into the setting page (as shown in the section titled "Change the way teams are displayed" then go down to Files and links

You can then change the File open preferences to Desktop App again it auto saves this change. Now if you go into a files section of one of your teams and double click on an Office document it will open in the desktop app.