If you do not have a citrus juicer, place the whole lemons on the counter and using the pressure of the palm of your hand, roll the lemons back and forth on the counter. This is going to help loosen up the juices and membranes inside of the lemon and make it easier to juice by hand. You can also microwave the lemon whole for 10-20 seconds. A warm lemon is easier to squeeze. Then, cut the lemon in half and squeeze it, straining out the seeds.