Glad to see my tips helped! Always a pleasure to help another player, even if I am an Undead player...
Footies/HMC does work, for the most part. Be careful, however. Footies kill Ghouls early on, but Crack Ghouls will easily tear through Footies. The backbone of the Human offensive line is the MK. Most Human players do this, and the UD players know this too, which is why you'll need to keep the MK safe. They will do everything in their power to keep him inactive, whether by death or simple Sleep Abuse.
Later on, Footies still work. But changing to Gryphs for higher damage output might be a better choice. You might be sacrificing a melee line, but the way the Ghouls drop will be a good idea. Take care to keep prying eyes (namely Shades) out of your base when planning this surprise or you just might end up with a nasty surprise of your own, mostly in the form of Gargoyles.
In the vs UD conflicts, go MK first. AM first, in my experiences from both sides of the playing field, is suicide. UD hero sniping is too good, and having a lower level MK is of no help against the Undead. A level 3 MK, UD will kill off with little to no hesitation, because he's not too much of a threat. A level 5 MK, then you have something they might think twice about fighting.
Other things you should take into consideration is the UD Triple Hero. Arguably the game's deadliest hero combination, their abilities at hero sniping are the most powerful in the game. A skilled UD player going Triple Hero against a skilled Human player going double hero will end up with hero levels of equal or better levels in favor of the Undead. It usually ends up level 3 DK, level 2 DL, and level 1 Lich (combined hero level of 6) vs level 3 MK and level 2 AM/Pally (whichever the Human chooses) for a combined hero level of 5. Not good. In addition, they can make quick work of the casters with Nova/Carrion. So watch for this.
Don't let him have his way with you in the early game. This is an excellent UD counter against HMC: keeping their numbers small. Crack Ghouls don't need Banshees or WoNs if there are only a few casters, like 4 Sorcs, 4 Priests. Some Human players skip the Barracks entirely in favor of upgrading to Keep earlier to get their casters out faster.
DON'T SKIP THE BARRACKS!!!
That is the biggest risk you could possibly take, and possibly the most fatal. If he finds you, you are in a world of hurt, and a lot of frustration. Don't talk about Militia. Militia will handle the Ghouls IF THEY STAND AND FIGHT. They won't. They want you to get Militia. A harassment on your base is them DARING you to get Militia, so you can hurt your own economy, while they run off and go do whatever it is they're gonna do. Meanwhile, you're in the middle of getting your economy back into gear while theirs has been running the entire time. And then they come back for another unexpected visit, maybe even blocking off the Town Hall to slaughter your Peasants as they come. I've done that a few times and, when pulled off, is usually end game.
Often, this will mean Crack Ghouls even earlier than you are ready for, and Crack Ghouls with 3/1 upgrades can take on a lot of Militia, especially with hero back up, namely the DK and the Lich.
DON'T SKIP THE BARRACKS!!!
The Footmen may slow you down, but it will guarantee you a measure of safety. Building 1-2 Guard Towers could help as well, but no more. Most UD players get discouraged when they see those Towers. I know I do. Who likes losing Ghouls in a failed harassment anyway?
If Abomshee comes into play, now there's trouble. Footies/HMC with MK/AM might be able to take on Ghouls/Banshees by eliminating the Ghouls during the AMS recast periods, but they have more difficulty against Abomshee. Despite Piercing vs Heavy bonuses, Aboms are far more resilient than their smaller, faster attacking counterparts, and Aboms, unless grossly outnumbered, can handle Footies easily. And tear through casters with equal, if not better, efficiency. Poly is the primary Human answer to tier 3 units, and AMS and WoNs will remove that. In addition, Aboms are less vulnerable during the AMS recast period, as they have more HP and are resistant to Clap and Blizzard, the primary counters against Ghouls. Not good. Going Knights to counter this is suicide. At worst, you are adding extra, unneeded units to the UD army through Possession so they can rip you a new one even easier. No need to worry. Gryphons will handle this. You just need to stay one step ahead of the Undead. Which is a bit difficult, since most times the UD is one step ahead of you. Don't worry about what I say. It's winnable.
Important note: Healing Scrolls. If the UD player decides he's gonna take the pressure to you with melee units, or AoE spells, you need to mass heal your damage. Priest Heal won't do it fast enough. Try healing 150 on all friendly units instantly with a Healing Scroll. At the least, take them to deny your enemy these same advantages. Ghouls can be powerful against HMC, but only if they have Scrolls and WoNs. WoNs, you are mostly helpless against. Scrolls, you can do something about by denying them. Buy a Scroll of Protection as well to make it tougher for the UD to kill your casters. Unlike you, he does not have a mass dispel unless he uses precious WoN charges to weaken you. And casters greatly benefit from the armor bonus, seeing as how they start with 0 armor.