TRUST!!! thats only way it'll work.. must be trust, be honest and open about everything, even your fears, i've been in LDR or going on 2 years now... he's moving down here in 2 weeks (finally!!! yay!!!) but it took a ton of patience and understanding on both sides, and the love to make it worth while!
Visit each other when you can, we tried or atleast twice a year, and use video chat programs often so you can see each other and see the love in each others eyes.
It is VERY difficult, and if you arent truly in love then its just not worth the effort.. but if you truly love each other you'll find a way