The short answer is no. There is no one “easy”, silver-bullet solution. What native users of English usually do to get around the problem is to use a mix of strategies that together work:
(1) Set up the use of he or she, him or her, and his or hers by first writing a noun to refer to: For example, write If a person has a garden, he or she should water his or her garden or The owner of a garden should water his or her garden.
(2) Pluralize the subject to allow for the use of they or their: For example, write Those who have gardens should water their gardens or the less common They who have gardens should water their gardens.
(3) Use the passive to allow for a change in subject: For example, write A garden should be watered by its owner.
(4) Use one:
Use of one is not incorrect. For example, write One should water one’s garden.
(5) Use a combination of the above at the same time:
For example, write One should water his or her garden.
The best practice, however, is to use a mix of the above strategies, so that no one strategy becomes so overused and monotonous that it draws attention to itself and distracts from what is written.