Initiative: We roll. Each PC rolls as usual a base initiative test (modified by talents or weapons), and notes success or failure levels. NPCs/monsters do so as a group (altogether or like goblins one initiative, orcs another). Then act in highest success levels to lowest (highest failure levels).
Capped Advantage: Max Advantage = Initiative Bonus. Though Advantage is easier to lose than many of its detractors think (any wound wipes out, any disengage wipes out, and lose 1 Advantage per round outnumbered), it can spike quickly.
No Advantage for Parrying: Though the rules say any successful opposed combat test gives +1 Adv., this is simply too cumbersome to track (especially for my NPCs). Advantage is also effective enough without giving an outnumbered opponent +4 Advantage for several successful parries. (However, I do provide +1A if you crit hit an enemy while parrying).
Deathblows: If you strike an enemy down to 0 wounds, gain a free follow up attack. Must be adjacent target or have quick draw type weapon (toss a dagger, bow-in-hand etc.). I like this rule, it's fun and not that difficult to track.
Larger Fear: The rules impose Fear tests when facing a foe Larger than you. This is too much and penalizes halflings (size Small) unduly, so I changed it to 2 sizes larger.
Platemail: while platemail is still pretty good at stopping many injuries, the rules do not reflect truly how protective this armor was. especially if we have guns running around, we can assume the full plate of the game is pretty advanced. Hence, in my games plate loses the 'weakpoints' quality and ignores all critical hits as long as the location is covered by plate. You're going to have to Hack the armor or whittle the platemail down.
This was too fiddly, a pain to track, and made the already resilient PCs too resilient for my taste. Accordingly, all humans start with 4 Fate, Halflings 2, and Dwarves and Elves 1. If you're a kind and generous sort, you can let PCs make an Endurance roll -20 or something to resist being stunned, etc. Any talents that provide resilience/resolve or rely on them work as normal, and treat each PC has having the resolve needed for them.
Reduced outnumbering bonuses:
While outnumbering a foe is great, and only attackers receive a bonus to hitting skill, I don't think it's +40 easier to hit an outnumbered foe in hand-to-hand. I cap the outnumbering bonus at +20 (and may one day only grant for 3:1 outnumbering). I also count a mounted warrior as 2, requiring 4 footmen to outnumber (makes sense to me given the mount's moving through the men makes even harder to hit).
Goal XP only:
No XP awards for merely playing the game and your PC not dying. Instead, you have to achieve things! I tried gold for xp, but this failed. I will give minor +10 to +25 in-game rewards for little stuff (fun roleplaying, a cool combat win, etc.). So:
+200 xp per minor goal or ambition achieved - this is your standard adventure, usually.
+500 xp per major goal or long-term ambition achieved - this is your long term plot points, ascension to knighthood, etc.
This also encourages updating and following ambitions more, as that'll give you healthy bonus XP along the way.
NPC and Creature Careers
This is not realyl a houserule as the game's rule creator, Andy Law, uses this method, but keep in mind the NPC and creature stats in the Bestiary are base racial scores. Thus, any experienced orcs or beastmen will have a couple career ranks under their belts. Even gobbos may have 1-2 ranks in stuff like Sentry or Soldier. To quickly come up with this stats: 1) take the base stats in the bestiary, 2) pick a few career ranks (eg sentry 1, or soldier 2), 3) add +5 per rank in that career to each attribute it applies to (soldier, 2 ranks: +10 WS, +10 BS, +10 T, +10 WP), and +5 per rank to each important skill - usually this means combat skills like Melee or Ranged, but Cool Endurance, Dodge, and the like would apply. Voila, a quick and easy way to generate fearsome foes!