This would be the list of stats by importance: Cha, Con, Dex, Wis, Int, Str
Pre-racial stats (point buy in parentheses) should be: Str 8(0) Dex 14(7) Con 14(7) Int 8(0) Wis 12(4) Cha 15(9)
After applying racial bonuses, your Cha will be 16 and your Str will be 10. If you don't want the Int 8, you can take 2 points from Wis to make them both 10s.
Edit: As for spells, grab Eldritch Blast (PHB) and Greenflame Blade (SCAG) as your Warlock cantrips. Hex (PHB) and Misty Step (PHB) should be on your spells known. For your tome cantrips, Shillelagh (PHB) lets you use Cha for melee weapon attacks and pairs nicely with GFB. Sacred Flame (PHB) is another good cantrip to get via your tome. As for rituals to add via Book of Ancient Secrets, I recommend reviewing the spells to find ones that you like.