1. Keep in sunniest spot where the shrub gets sun from sunrise to sunset. 

2. Water only when top soil is dry upto 2 inches. They donot like wet feet. Mostly frequency for small plants is only once a week, big ones more infrequently ie., once a fortnight water deeply. 

3. Watering too often leads to root rot and draining of nutrition. The roots r shallow and frequent watering deprives it of nutrition and susceptible to pest infectation. Spray/bathe it with neem oil with some soap emulsion (to make neem oil mix in water) regularly to keep pests away on plant and soil. 

4. Citrus shrubs r high feeders and require varied nutrition like vermicompost, old cow manure, bone meal, etc when in season. Once a month, 2 days before watering, dig up top soil upto 2 inches to help aeration and break up small roots and create stress to produce fruits. After 2 days, add manure and water thoroughly.