I have had a lot of success with this relatively budget deck on untap.in, but I'd always love more suggestions. I'll break it down with the most important cards first.
Creatures:
Fabled Hero
really lives up to his name, bringing double strike and heroics in the form of a 3 cmc creature.
Akroan Skyguard
gives you a heroic creature automatically with a form of evasion.
Favored Hoplite
makes for a fast game and a good answer to aggro and burn.
Hero of Iroas
is honestly a filler heroic creature to me, but can make for some interesting turns when you can suddenly play a lot of auras at once
Enchantments: Ethereal Armor is commonly known as the bread and butter of a heroic deck, and I would agree! Whether it's needing that first strike to deal with pesky suicide death touch creatures or needing that boost of damage to wipe out your opponent in one turn.
Gift of Orzhova
is a close second alongside Battle Mastery. Not much explanation is needed for these cards.
Ordeal of Heliod
earned it's place in my deck when during playtests I would use 2 at once to earn 4 counters and 20 health in one turn.
Bonds of Faith
is a fairly uncommon choice, but considering every creature in the deck is human, it has nice utility to be a pump or a control.
Other Spells:
Gods Willing
is well known for being the number one choice in protection for a heroic deck, but I've also seen a lot of suggestions for Emerge Unscathed. I'm not sure if the scry or the double effect is more important, although I'm leaning towards the double effect.
Now I should point out that there are VERY viable builds found in White/Blue and White/Green. I enjoy running pure White because it cuts out a lot of "mana screw" and keeps the deck much more budget.
If you want to switch to legacy, the only suggestion I have is adding a couple Winds of Rath.