The best advancement Pathfinder made was a guide for a GM to create races. Yes, it is flawed. It is still a guide and far better than 3.5 asking people to look in he monster manuals and guesstimate if a home brew race was suitable.
Well that was the default way of doing it. The more advanced way was to buy the Savage Species rulebook. It had rules for determining LA. Again, just like with PF, the rules weren't perfect and D&D didn't follow all of themselves, but let's not suggest there wasn't any guidance given, you just had to pay for it.
Instead of, say, having the Monster Hit Dice 'buy back' some of the Level Adjustment.
Actually I think that was the way it worked. It was basically a 2 racial HD = 1 LA trade. So a race that was suppose to be LA 4, might be 4 racial HD and LA 2. This was because too much LA (being just empty level slots in 3e) would make the creature way too weak. The compromise was to give it some HD in exchange for some of the LA.