I spend a considerable amount of time using SQL Server Management Studio,it's the GUI interface to Microsoft SQL Server (Server and the free Express edition). There's an add-on called SSMS Tools Pack which adds some new much needed features. This tool used to be free (or donation-ware), but since version 184.108.40.206 it's a paid-for licensed tool. I still use version 220.127.116.11 which doesn't require licensing. It has a number of features, though I'll only cover the ones which I use and now find indispensable:
Once installed it adds a new menu item (SSMS Tools) on the top menu and a new context menu or right-clicking of an object (SSMS Tools).
This colours query windows based on the server name, so you could colour live/development/test servers differently. I normally switch between servers several times and this gives me the confidence that I'm running the query on the correct server.
It's not perfect as other windows aren't coloured, i.e. the table designer, but hopefully this will come soon.
Generate Insert Statements
This, as it name suggests, generates insert statements for the data in a table. This allows the query to be copied and run on a different server, or maybe stored in a source control package to keep a history of data.
Query Execution History
This saves all queries run into a local folder, by default c:\SSMSTools\. This can then be queried by date and the resulting view shows all the SQL commands run on that date - also the time is displayed. There have been a number of times where I've written an ad-hoc query and not saved it as I thought I'd never need it again, only to find that I needed to perform a similar task at a later date.
Similar to snippets in Visual Studio - these are snippets of code/SQL which can be entered using short-cut text entries. It comes with a number of built-in snippets, for example entering UPD and then pressing Enter adds the following snippet which can then be amended.
I've added a number of my own snippets, a few examples are below.
SELECT TOP 1000 *