So, the big thing that helps keep your line intact is inspiring. Word is 1 source of inspiring per 500 points in armies with low defense values, and 1 per 1000 even in high def armies. That said, abyssal guard are def 5+ with regen, so they are a good anchor unit. A regiment of guard can take on average 20 hits at crushing strength 1 before breaking- 2 turns form a high output unit, so you might last a third turn with regen.
Also don't overlook succubi- stealth and ensnare is really good, and they hit like a ton of bricks (especially with the magic items that gives the crushing blow 1, or elite).
You also have a couple options for very cheap chaff- larvae, imps, and fleshlings. Larvae look like a decent tarpit as well.
You also have a good number of flyers- gargoyles, tortured souls, and darn near every hero. Flyers are very good, especially for hunting shooters, and forcing your opponent to react to you.
As for list building, they seem like the sort of army where you take one of everything, and each thing has its job. Even regiments of regular abyssals unlock character slots, which is look fairly central to an Abyssal strategy.
Does that help?