Best way to back up

I was thinking of  getting a usb 3.0 external drive to back up all my songs and all my samples.  Is this the best way to do that?  

I recommend you consider keeping backed up data offsite, as one forum member had an entire studio cleaned out, including backups from 10 years of projects.
 
I picked up a USB 6 TB external backup drive for less than $200, and LOVE it.
 
Of course, my mom had a Life Alert device for a whole year before we discovered she had never taken it out of the box, so DO use whatever backup device/approach you end up getting. :)
 
Bob Bone
 

I use OneDrive now for my offsite backups of actual songs and I have about 7 drives I use for everything else on-site.
 
The issue I'm having at the moment is doing backups of libraries/installers/etc. I find I'll buy something like a Konakt library and forget to update my backup for sometimes a month. I'm currently looking into some new folder mirroring software that I can run at the end of the day to make sure everything is up to date. The problem I've had in the past, especially with manually moving things, is that it takes too long to go through every single file in Windows to see what's new or changed because of the amount of files some of these sample libraries have in them.

I use Acronis, a USB3 dock with SATA drives and a couple of NAS drives.
 
Acronis runs 3 jobs every night:
1.  Windows; drive C to the USB dock.
2.  Everything else to the USB dock.
3.  All audio project folders to NAS.  This duplicates the audio project backup done as part of (2).
 

from my days as an IT consultant specializing in Information Risk Management (some of the stuff we used to preach turns out to be true - who knew?)
 

• You MUST maintain, at a minimum, three copies of your data
• You MUST back up to different media (back then it was disk, tape, and optical)
• You MUST back up to different locations
• You MUST test your backups!
• You should, for efficiency, divide your data into stuff you can re-create, stuff you can't (easily) re-create, and stuff you don't care about, and play your backups accordingly.

That last part may not be as important as it was 15 years ago, storage has gotten dirt cheap. I don't fret over the difference between the three categories as much as I used to, but I still pay attention.
 
In  practical terms, and my strategy is constantly evolving, my current scheme includes:

1. Regular "image" copies of my OS & Apps drive - regularly being defined as whenever I make a major change, or once a month, and if I don't I can re-install everything, but I do not look forward to that!
2. Regular file by file copies of my samples drives - as above I could re-install the libraries if I had to, but with most libraries being downloads it is not as simple as when they all came on physical media, and at 1TB I really don't look forward to that task, so I try to back it up every month as a whole - I think incremental backups for a 1TB drive don't make a lot of sense since so little changes, and if I had  to go through several backups to get everything I'd be better off starting from scratch.
3. Daily (and by daily I mean any day I work in the studio - sadly there are days when I don't) incremental backups of my data drives. This includes all  my projects, not just music projects. These backups are made to a pair of 4TB  USB3 external drives that get swapped. Both are in the house, but only one is ever in the studio.
4. I don't have a solution for downloaded installers yet - for now they get backed up as part of #3 above. I need to do better!

I also keep a copy of all my data files in the cloud - I use several services because I can't fit everything into my 1TB Dropbox account any longer. I also backup my work laptop and my wife's laptop to the cloud.
 
If I had the time and money I'd like to trim this down to the same timetable, but everything gets backed up to a NAS device that  lives in my home, and is mirrored to another NAS device somewhere off site, maybe a commercial cloud offering, maybe  not.

The key, for me, is three copies (the computer itself. a local backup drive, and a remote backup).