What i tend to do initially is have 2 'runs' next to each other where the rabbits can see each other and sniff through the wire. They get swapped into each others runs every day, so they get used to each others scent, etc. After a couple fo weeks we try them together, while supervising them, we tend to put the more dominant rabbit into less dominant's run. As long as there is no overt aggression we leave them together, for a couple of hours. We do this extending the time until they seem happy together, at that point we only seperate at night. When we feel they are acting as a couple we leave them in the run, it gives them more space to get away if anything goes wrong. Finally they go into, usually a neutral hutch.
This bonding method is slow, and can take us a couple of weeks to a couple of months.
Ziggy and Sorrell took about 6 months in total, I think. Sorrell had a small bout of stasis as they were put together, so we stepped back and slowed down again. They are now in the run 24-7, although I'm still not fully confident about putting them in a smaller space.
This morning was the first time I've seen Sorrell go up to Ziggy and ask for a groom, and he obliged.