The best candles of the age were beeswax, but only the wealthy could afford these, and even then, they were saved for special occasions since the tax was so costly. So sought after of a commodity, senior servants would be allowed the remnants of unfinished beeswax candles in order to sell them (or use them). They burned for an hour, and so had to be swapped out throughout the evening during a ball or night's entertainment.

Tallow candles were the most commonly used for daily use. Being made of animal fight, they smoked and smelled, but they lasted 20-30 minutes, and were fairly affordable for those of the middle-upper income brackets. The wick had to be trimmed every few minutes to keep the flame from guttering as the tallow melted.

Rush lights were all some families could afford, and they were downright dismal, as they were not actually a "candle," merely a wick dipped in animal fat. Lasting only about 15 minutes, they provided as much light as a modern match, guttered, smelled, and dripped. Best advice? Keep the window open and work quickly.

To make the most of candlelight, mirrors and fishbowl-shaped glass were used to create reflection. Mirrors were expensive and difficult to make, however, so this was a lovely trick predominately for the wealthy.

Interestingly, tallow candles are a popular choice these days for homemade candles, but now they're usually scented with oils and involve a slightly different production process to avoid the smoking and the smell.

Not to be missed is this article from Pen and Pension:

The Cost of 18th-century Lighting