When a new player started playing with us about 6 months ago, she had exactly that problem. My solution was double.
She wanted to play a druid, so there were lots of spells to choose from. I've therefore reduced the list of 7 cantrip spells and 16 level 1 spells to a list of 3 cantrips and 6 spells (the first level druids choose 2 and 4 respectively).
In my case, she did not know what kind of role she wanted to occupy, or what sort of things she wanted out of her spells, so I chose a decent range of generally useful spells. If your players have a better idea (healing, DPR, charm, illusion, utility, etc.), you can customize the selection accordingly.
I strongly suggest that if you do it for a spellcaster with a semi-permanent spell selection (Bard, Eldritch Knight, Ranger, Arcane Tracker, Sorcerer, Warlock, Wizard), you allow them to change their spells more often than what is allowed in the books. they learn what they like and what they do not like. For example, if your bard discovers that he is not a fan of Charm Person, let him exchange it for free, even if he has not upgraded yet.
I also did it for my new player, as Druids frequently change their hex. I have written brief descriptions of each fate and their overall purpose. Some examples:
Shillelagh – hits better
Entanglement – slowing down movement in an area
Faerie Fire – Disable Invisibility and Facilitate Strikes
Thunderwave – Zone Damage Right Beside You and Stay Away
In this way, she had a quick idea of what each spell was doing and could make the choice from there.
This method seemed to work well, although it was a sample of 1, so YMMV. I think that requires some trust between the player and the GM (since the GM is reducing his choices), but it quickly sets them up and if you allow them to change afterwards, it will not penalize them. their choices, which will facilitate their choice.