Vampirism is most beneficial for this kind of class, but not a requirement. Beyond that, the choices are yours as far as non- combat perks. The general rule of thumb for the Assassin build is to pump your perk points into one-handed, dagger, and sneak (specifically the - Assassin's Blade Perk), light armor, and fill the Archery tree. Also points should be added to Shields, One Handed or Two Handed, depending on your style. The main idea behind a Paladin class is being a strong melee user, with the assistance of magic, so the key choice here should be Restoration and Heavy Armor, along with Alteration for the armor increases.
This is because destruction magic is very underpowered at higher levels and your best option in battle is to stun lock enemies with dual cast, making you practically invincible in a 1 on 1 fight. Tip: If you plan to base your character's offensive ability mainly on Destruction magic, its advisable to enchant your clothes/armor with 100% destruction magic mana reduction. One or two points in Light Armor to help survival. A warlock is based almost purely on Destruction magic, so clearly pump points there, with some in Conjuration and Enchanting.
