Many people find it difficult to achieve a satisfactory level of effects from the leaf in its natural state.
Here's why: The active principal of Salvia divinorum is a diterpenoid compound called salvinorin-A. The average concentration of salvinorin-A in Salvia divinorum leaves is 2.5 mg per gram. A moderate smoked dose of salvinorin-A for a person of average sensitivity is 0.5 mg. Therefore, in theory 200 mg (1/5 gram) of Salvia divinorum leaves contains enough salvinorin-A to produce moderate effects. In practice however, one should assume about twice this dose (i.e. 400 mg, or 2/5 gram), because some salvinorin-A is probably decomposed during burning, some is lost in smoke that escapes during smoking, and some is not fully absorbed in the lungs and is thus lost upon exhaling.
400 mg. of Salvia divinorum leaves produces a fair amount of smoke, and it takes several large lungfulls to inhale it all. Because salvinorin-A is rapidly metabolized in the body, it is essential that the full dose be ingested within a 2 - 3 minute period. It is also essential that the smoke is absorbed as efficiently as possible, otherwise much of it will be wasted. People vary in their ability to inhale and retain large amounts of smoke. Some people have no trouble achieving strong effects smoking ordinary leaves; others find it very difficult.
The potency of Salvia divinorum leaves is somewhat variable. So far, no one has identified the specific environmental factors responsible for this. Obviously, it is easier to achieve effects when using leaves of higher potency.
People vary in their sensitivity to salvinorin-A. Some people are highly sensitive and have no difficulty achieving a profound level of effects; others are extremely insensitive and require a dose 2 - 3 times higher than average.
ADVICE:
(1) Use a water-cooled smoking device (a water pipe, or bong). This makes it much easier to inhale large quantities of smoke. Because the smoke is cooled, it can be inhaled more comfortably without coughing.
(2) Try to inhale the full dose in three lungfulls. Each one should be inhaled slowly and deeply, then held for 20 - 30 seconds before exhaling. It is very important to retain each inhalation of smoke deeply in the lungs long enough for it to be absorbed efficiently. Do not pause between lung fulls (except for a short breath of fresh air if necessary). This insures that the whole dose will be consumed within the 2 - 3 minute period required. If the dose is smoked too slowly, it will be metabolized faster than it is ingested.
(3) Use a 'micro-torch' type lighter. Many people report better results when using this type of lighter. These produce a very hot torch-like flame that causes rapid combustion of the smoking material and hence produces more concentrated smoke. Because of the extra heat generated by these devices, it is important to use them in conjunction with a water-cooled smoking device.
(4) Use extract enhanced leaves (fortified leaves). These products are concentrated, so that the entire dose can be more easily consumed. Some of these products are so refined and concentrated that a full dose produces no more than a tiny wisp of smoke. These products also have a health advantage, since they reduce the amount of smoke that must be ingested to achieve the desired level of effects. One must keep in mind however, that fortified leaves must be used more carefully because of their greater potency. These products do not need to be smoked in a water-cooled pipe. You can make crude extract enhanced leaves (5x, 6x, etc.) yourself quite easily. Instructions are available in section XIII of the Salvia divinorum FAQ at: http://salvia.lycaeum.org/faq.html. Similar products are available commercially. You may also want to consider one of my standardized salvinorin-A enhanced leaf products, which are available at: http://salvia.lycaeum.org/salviashop.html.