I personally think some of the best casters focus. In this case I'd chose a single spell for Spell Perfection from the necromancy school and work it. Have all of your feats still be viable for the other spells though as well.
Some spell ideas are Vampiric Touch, Suffocation, Banshee Blast, and Finger of Death.
Vampiric Touch is a great spell if your planning an Eldrich Knight. The reasoning for this is the fact that its a touch spell so having the high BaB from EK coupled with EK's cap stone is great to get the spell going. Having a high crit range weapon will almost guarantee getting the quicken off for some nice temp hp and damage. The Feats id suggest for making best use of this spell is Spell Perfection, Maximize spell, Empower spell, and Intensified spell.Using Spell perfection will make Maximize free and combining Empower and Intensified will raise it to a 6th level spell but the damage and temp hp will make you a great front liner.
Suffocation is a great spell to abuse if u want to guarantee death to a single target. Feats to use for this spell is Spell Perfection, Extend spell, Reach spell, Persistent spell, and (Greater)Spell Focus. The idea of this combo is to extend the rounds of potential success and make them have to make to saves per save to stack the odds in your favor. Spell perfection is mainly to double the bonuses gained from Spell Focus.
Banshee Blast I would abuse in the same way as Vampiric touch when it comes to feats at least. I would also add the Spell focus feats to that list since it does have a save though the spell focus feats are just good to have for most necro spells since there mainly save spells.
Finger of Death is a spell I'd highly focus upping my saves and caster level for. The main thing id do with the spell is use the Reach spell to snipe targets from a far.
To be honest your feats would depend entirely on the type of character you want to make. The examples of all the spells to abuse are mainly for your typical stay in the back caster, minus Vampiric Touch. In concerns to making a cleric necro your best bet is to focus on the Reach spell so you can make your Inflict spells useful for damage.