If you have an hp 8610 printer DO NOT upgrade yet.
To save yourself frustration, don't upgrade to Win10 yet. Too many issues.
To upgrade to Windows 10:
http://msft.gq/gxn/GXN is a small utility that helps you upgrade your current Windows 7, Windows 8.1 or Windows 10 Preview installation to Windows 10 RTM without any waiting or reservation.
This tool provides a few enhancements over the Media Creation Tool from Microsoft. As an example, GXN is able to identify and clean up temporary files from previous failed installation attempts, thus lowering the chance of setup not working significantly. GXN will continue receiving updates for the app itself and will always provide the most up-to-date copy of Windows 10 Microsoft offers.
These are the following prerequisites you need for GXN to work properly:
.NET Framework 4.5
Windows 7 or newer
An active internet connection
Administrator rights
Please report any bugs you've found using DMs on Twitter, @Whistler4Ever.
If you want to install Windows 10 on a computer that does not have an internet connection, use this:
https://www.microsoft.com/en-us/software-download/windows10