Method 1:
You can go to the reputable and free ringtones sharing website (my example here: ringtonescloud.com).
Find and hear
Once the ringtone sounds as expected, download and install it.
Method 2:
If you choose the first option, sometimes the website doesn't have the ringtone you want. So I'm going to show you how to do the following steps to make the ringtone you want:
Go to mp3cut.net and upload your favorite songs
Select a piece of the song you want to use as your ringtone, cut it out and save it.
Set the ringtone.