How do I know if an attorney is good or not?

Let me clarify a few points, here.

I’ll be filing for my five-year-old son. His disabilities are severe enough that he needs a great deal of therapy (speech, occupational, physical), and that’s expensive. The cheapest I’ve found around here are $70/hour.

The person with whom I spoke at the SS office told me I’d need info about his biological father and his whereabouts, and as I’ve had no contact with him for nearly five years, I’m hiring a PI to find him. I haven’t a clue whether the guy is alive or dead, let alone where he might be now. I wouldn’t know where to begin looking for him, so I’m handing the matter off to a professional. (Long story made short: death threats, assault charges, attempted kidnapping, restraining orders, breaking & entering charges…)

We (my husband and I) are fairly poor, but my mother isn’t, and she’s more than willing to foot the bill for the attorney. Same goes for my husband’s mother and father, so we’re not terribly concerned about finding the cheapest lawyer – just the best. I’m trying to plan ahead, so I’m gathering all the information I can now.

Again, thanks for all the input. I welcome any more advice that anyone cares to offer.