Mike,
I have had the best results by trying to rough cut the curve as close to the finish cut line as possible. The less material that there is left to remove with the router, the cleaner the cut tends to be. Climb cutting can help, but when you are going across the grain, a certain amount of tearout is almost inevitable. It also goes without saying that the bit needs to be very sharp. That is where the extra money paid for the best quality bits really pays off.
As far as RPM's are concerned, it is really dependant upon how fast you are feeding the router. The higher the RPM, the faster the feed rate needs to be. Intuitively, one would think that if you run the RPM's up, and slow the feed rate, you will get a smoother cut. The problem is that when you do that, you also increase the heat generated. That can result in burns in the wood, and worse yet, overheating the carbide in the bit which drastically reduces but life. Overheating probably causes more premature dulling than any other cause. Ideally, you want to produce a certain chip size, or as it's called by bit manufacturers, the chip load. Some manufacturers have charts on their websites that show the ideal chip load for a given bit, and a formula to calculate the RPM and feed rate necessary to create the proper chip load. Onsrud has extensive charts available on their website, downloadable as PDF files.
One seat of the pants way that you can judge if you have the RPM and feed rate right is to see if you are producing little shavings or chips or dust. If it's dust, something's wrong. Also, if everything is OK, you should be able to touch the bit immediately after cutting and find that it is just warm. If it's too hot to grab on to, then either the feed rate is too low, or the RPM too high, or both.
Hope this helps.
Matt