It will cost a little money but this is what how I got to Linux. (Maybe $30?)
I was never able to successfully dual boot. I know it can be done, others do, I couldn't get it to work. If you have an older Dell, the hard drive just sits at bottom edge. I purchase another hard drive, (maybe eBay since it is an older style of hard drive) and just physically swapped out the drive, basically running Linux. I choose Mint-Cinnamon. There were a few times I needed to used Windows, such as my Scan tool software or FitBit so I would just install the Windows Vista drive. On many laptop computers, (you didn't state what model you have) you can purchase a hard drive adapter that inserts into the space of the CD-DVD slot. Yes, you can't watch DVD's will this is happening, but if you want to learn without danger to your current system.
You can install Linux by making your USB drive into a boot-able device. That step has become really easy. ANd a total, with update and format of a hard drive is < 20 minutes. Just did another yesterday.
The big advantage to swapping physical hard drives is you can start trying all different flavors of Mint within any worry when you reformat a hard drive. You not playing and accidentally deleting the wrong ( Windows) partition.