If you're starting from a blank UST, you can use AutoPitchWriter to add some basic pitchbends and vibrato to the notes.
After using the plugin, you can go through the UST and make final adjustments. You can also customize the UST in the plugin folder with your personal style of pitchbends, so that it uses those every time you use the plugin.
For references, try listening to other versions of the same song you're covering, including covers sung by human singers. Pay close attention to how they sing the pitch of the notes, which notes have vibrato, how words are pronounced, where they pause and breathe, and so on.
If you have a vocal-only audio file, or if you record yourself singing the song, you can open it in VocalShifter LE in order to look at the pitchbends.
When looking at the shape of the pitchbends, you should also listen to that section of the song, so that you can learn how the pitchbends match up to the sound.
For additional music practice, you can try these ear training exercises. They're a bit tough and are more focused on general music theory than singing in particular, but this can help if you plan to learn more about how songs are composed and want to analyze the songs you like.
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Introductory and intermediate music theory lessons, exercises, ear trainers, and calculators.
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