When starting out with bees, I always suggest that new beekeepers buy the biggest smoker they can find, preferably one with a protection cage and a hook for placing it on the side of a box or hive toolbox. My experience has been that most beekeepers increase their hive numbers this requiring a smoker that continues to smoke for hours at a time.
Having said all that, I use little smoke if any, but always have a smoker lit just in case.
If you have a new smoker and it has a loose plate in the bottom, be sure to stand the legs up so the plate is higher than the air hole. From time to time this may need checking. They are made from a flimsy piece of metal and get pushed down when adding fuel.
With fuel, many of us use dried pine needles as it is critical the smoke is cool so it does not harm or disturb the bees. When collecting pine needles use only the freshest on top and avoid any old moldy pine needles as this is toxic and nasty on bees.
Other people use damp hay (not mouldy), toilet roll cardboard, wood chips... however all of these products need to be tested for coolness by puffing the smoke onto the inside of your wrist or other sensitive skin. The smoke must be cool. If I source pine needles from somewhere other than my regular trees, I test the coolness of the smoke.
There is a knack to starting a smoker. Take a handful of needles and light them. You want a strong flame so add further needles to achieve this. Then it is time to pack the smoker full of needles, working the bellow to add air. Push all the needles in with your hive tool and close the lid, adding more air if needed. A well packed smoker can burn for hours.
Ensure the smoker is creating smoke with little effort. Look closely to ensure it is not ash being pushed out from the bottom of the smoker. Bees do not like ash and it will not disarm the guard bees.
At the hive, use a little gentle smoke at the entrance to disrupt the communication of the bees and then wait for 20 seconds before opening the lid. I rarely need any smoke at the lid. The bees are usually working away quietly and will remember from past experience that you are slow and gentle with them.
Use smoke only when needed as too much smoke can agitate bees. Interestingly, the best use for the smoke is to cover a bee sting which stops the alarm pheromone and prevents further bites, or to cover a suit so the smell does not annoy the bees.