Now I don't know much about nothin' other than Greece and East Rome, but if I had to speculate, perhaps having a rather good leader like Senhor Louverture take charge and bring industrialisation to the island and get ex-slaves, most of whom are either out of a job or share-croppers post-Emancipation, to become workers in the country's new factories. Now, I'd take it that if the island has a nice balance of agriculture and industrialisation, in time in can create a service-based economy and be a rather nice place to live. Perhaps it might also help to bring in immigrants who have experiences with building up industrial bases, too. It might even make Haiti more interesting with say Japanese or German (or French, I guess, but I'm the most anti-French person that you'll ever meet, so personally out of emotional reasons I'd advise against it) immigrants.
And after a few decades of hard-work, Haiti can sit back, relax, and tell France and the United States "Well, I did this all on my own. Fuck both of you two".
Also, avoid a political-culture of corruption and bad leaders at all costs. The military also needs to be separated from the legitimacy of the government. In the late Twentieth Century, Mexico took power away from the military by making military leaders rotate through posts so they couldn't gain a power-base in any region, among other things that I can't remember, too.
Also, maybe by answering questions, people will know who I am since I'm positive that only five-seven people know who the Hell I am and I've been here for nigh three-years now.