W/B Good Stuff

White:

Silverbeak Griffin (Mono-White/Heavy White only)
Pegasus Courser (You need to have grounded creatures with decent power for this to be effective)
Leonin Warleader (A good source of lifegain, very good with pegasus courser)
Star-Crowned Stag (His ability to tap creatures is very strong when you want to apply pressure)
Herald of Faith/Serra Angel (Fulfill similar duties)
Serra's Guardian (A more expensive Serra Angel, 5/5 has some benefits, otherwise 6 drop is worse than 5 drop)
Zetalpa (Expensive, do not run around aggressive core)
Luminous Bonds (Best removal white has at the start)
Angelic Reward (A very meh card, but can be decent if you can slap it onto a 3 power creature with no flying. Deck building dependent)
Take Vengeance (Poor removal, but it's better than nothing. Replace with better options if possible)

Ajani's Pridemate (You need lifegain cards, but is a decent payoff if you have some. You prefer cards that can lifegain more often than once for this card)
Bishop's Soldier (Probably the most stable white 2 drop you can play without having to invest heavily in white)
Paladin of Atonement (This one is eh, 1/1 isn't good stats but can snowball out of control, you can try this and see if you like it)
Inspiring Cleric (Better Loxodon)
Resplendent Angel (Obviously good, you want to be white heavy to run it though)
Moment of Triumph (Ok combat trick, you want to have more white mana preferably to play this, it's also not self sufficient, need a creature to be effective)

Black:

Deathbloom Thallid (Decent body, leaves a body when it dies, ok card)
Hired Blade (You don't want to run this unless you're pushing for mono-black and you ran out of cards)
Skymarch Bloodletter (2/2 flying can be valuable)
Gravedigger (Particularly useful if you have important cards that can die often)
Vampire Sovereign (3/4 Flying with 3 Drain is VERY good at a lower power level, don't be fooled)
Gravewaker (Expensive, do not expect you will get to use his ability often before they remove it, but is a good late game drop if they can't remove it)
Skulduggery (Ok combat trick, you want to be black-heavy to use it)
Murder (Strongest removal available at the beginning, you have to be black heavy to hit it consistently)
Strangling Spores (Eh removal, more splashable compared to the previous two but is not too effective)
Rise from the Grave (It's ok, 5 mana reincarnation isn't the best but it's worth playing around with a bit if you're into it. Need decent reanimation targets)

Sanctum Seeker (You have to play vampires to get use out of this, but it's very good in that condition)
Champion of Dusk (Also have to play vampires. You can still play it if you want, it just says 4/4 pay 1 life, draw 1 if you don't run vampires)
Epicure of Blood (If you want additional lifegain payoffs. Personally I didn't like this card too much, but you can try it)
Nightmare's Thirst (Skulduggery is better without lifegain. With lifegain it can be better. Try at your own discretion, you want to be more black-heavy)
Vraska's Contempt (Insane removal, slower than Murder but more effective against many things which you may or may not see. 2 life is also meaningful)

W/B cards:

Legion Lieutenant (You have to play vampires for this obvs, but it's a good card if you do)
Call to the Feast (Unless you care for life gain or vampires a lot, I feel this card is underwhelming compared to the white 4 drops. Try it if you want, it's not BAD persay)

General thoughts:

You want to "splash" higher cost cards (4-5 generally) that require only 1 colored mana source and keep double mana source cards as the heavy-color sided favorites
You also want to try to favor the color that has more of your early drops (1-2-3)