The first burn is the most important.
When you light your candle for the first time, be sure to wait until the wax has melted evenly over the entire surface of the candle. Making sure the entire surface has melted before extinguishing your candle will prevent tunneling and help your candle last longer.
Burn your candle for 3-4 hours at a time .
Even if you want to burn your candle all day, to make it last as long as possible (40-50 hours), make sure you don't burn it for more than 3-4 hours in a row. However, if you choose to burn it longer than that per session, that means you'll need to buy a new candle a bit sooner.
Trim your wicks.
Before relighting your candle, be sure to trim the wick to a quarter inch to ensure it burns as smoothly as possible.
I'm sure you know the right way to go. Do not leave your candle unattended and keep it away from young children and pets. It might sound like common sense, but as a firefighter, I'd feel bad if I didn't mention it!