Being nocturnal, geckos prefer to feed at night time and usually become active at dusk in the wild. In captivity we use artificial lighting to produce this affect thus triggering feed times. While our lights may be on in our living space the gecko will react to their lights going out in theirs. The easiest way to go about this is to set your lights on a timer to go out in the early evening.
Leopard geckos mainly eat insects like crickets, meal worms, superworms, silk worms, and wax worms. They will also eat some commercially prepared foods, but I personally have not had any luck with these products. Pinky mice are also offered once in awhile as a treat or to fatten up breeding females. The food source must not be to big because geckos do not chew their food but swallow it whole. Geckos do have teeth but they use them for holding their prey and not for chewing. I feed my geckos every 2 or 3 days but this is not written in stone. Sometimes I feed them every other day, but never more than 3 days apart. I tend to give my male 4 gut loaded superworms and my female 8 gut loaded meal worms. Both of my geckos will not eat crickets, but wax worms and silk worms are added as treats once in awhile. My male loves pinky mice but the female is scared of them along with superworms.
Some people like to feed their geckos in the cage so they can watch it hunt its prey. This is alright to do as long as you realize the problems that this can cause. A problem that can occur is that the insect will hide and then come out when your gecko is asleep. This can cause stress if your gecko keeps getting woken up by them. Crickets when starving will actually try and feed on your gecko which in turn can cause infected wounds. Another problem is the insect that is hiding will lose its nutrients over time and also may feed off your geckos own feces. If you suspect that an insect is hiding you may try to draw it out of hiding by adding a small piece of carrot in the enclosure.
Feeding bowls are a common way to feed insects to your leopard gecko. The bowl should be smooth and deep enough that the insect cannot escape. Removing the back legs of crickets will prevent them from escaping. Keeping a piece of carrot in with the insects will keep them nutritious and hydrated.
Dusting insects with vitamins and minerals is a very important process for your geckos health. There are many different supplements available, so ask your supplier which one is right for leopard geckos. Follow the manufacturers instruction on how often to add to food supply. To dust your insects you can use a baggy or small bowl with a lid, just add supplements and insects and shake. You can also purchase commercially available dusters that allow the powder to settle to the bottom after you flip it over. This allows you to reuse the supplement for the next feeding.
Water should be provided for your gecko at all times in a shallow dish. You should clean this dish every time you change the water. Changing out the water every third day should become a common practice along with removing feces in the cage. Insects drowning can be a health issue for your gecko. Adding a rock into the dish allows the insect to climb out.
I like to gut load my insects with nutritious foods prior to feeding to my reptiles. I make up a mixture of fish food, 5 grain cereal, powdered milk and rolled oats. This is added in at all times for insects to feed on, but you may add in only 24 hours before feeding time if you wish. A piece of potato, sliced orange and also baby carrots work as a water supply while also delivering nutrients. Most pet stores also sell commercially made gut load and water gels. Either way you go the nutrients are passed on to your geckos when they eat your gut loaded healthy insects.