A few very broad guidelines. They provide a starting point, but they can't guarantee balanced LAs (especially not compared to each other).
For races directed at fighter types:
Probably every 2-4 points of Strength Bonus (beyond that of a Half-Orc or Orc, with the associated penalties) are worth one point of LA. Though for a "fair" LA, you will also need to slightly boost Constitution (to compensate the HD loss), maybe by +2 for every 6-8 points of Strength.
So, a "Brute Monster" that grants a +8 bonus to Strength and a +2 bonus to Con should probbly have an LA around 3. (Note that the Half-Dragon Template probably grants more than this for the same LA, indicating that it is only a starting point)
For races with spell-like or supernatural abilities:
The LA should ensure that a unclassed character does not have access to (significant) spells or spellike abilities beyond its ECL (Racial HD + LA). A creature that can cast Fireball 3/day per day should probably unattainable before Level 5 (where a straight Wizard would get the ability to cast Fireball, too). As a guidline, the spellcasting ability score (with a straight 10-11 base stat) should probably be high enough to allow a spellcaster to cast the equivalent spell.
So, a "Fireballslinger" Monster that can cast Fireball 3/day should probably have a Intelligence or Charisma modifier of +2 to +4 and an LA of 5.