Oh boy.....
In my opinion, your BEST hitter should be on the opposite. Your OHs should be extremely consistant hitters but your Opposite should be your big gun. The reason for this is that when you get bad passes or broken plays you throw up a nice high 4 ball to your OHs and let them hit, but when you have a good pass a good setter will give the Opposites 1v1s nearly everytime and with a big gun hitting 1v1s thats a point the majority of the time. If you look at the US national team in the FIVB world championships that I posted about a while ago here:
VOLLEYBALL: U.S. Men's National Team Journal for Nov. 27
Reid Priddy and Riley Salmon are great OHs because they can get up and put a good hit on anything, but Dave McKenzie is the big gun at opposite, racking up most of the kills.
Now the biggest mistake is actually thinking there is a difference in the footwork/swing. The difference is in the timing. When starting your approach you want to stay open to the setter with your shoulders and then you must allow the ball to go past your nose and to your right arm (I assume you are righty) as you jump up to meet it and REACH!!
What I've found with working with people who are new to the game is that when they are on their opposite side (lefties on OH and righties on Opp) they tend to reach higher to contact the ball then they usually do. What I mean by this is when new players start hitting, alot of times they will have a bent elbow or they will not use their other arm to "find the ball" a la bow and arrow, and thus their contact point is low. When hitting on the other side they end up reaching higher because they want to swing at the ball as soon as it is close enough to hit so the ball is at a higher point in its tragectory.