Florida is a different animal, but here in Vegas the main keys to success with citrus (particularly picky ones like variegated varieties) are as follows:
1. Keep soil slightly acidic (shouldn't be an issue there at all).
2. Feed with citrus specific fertilizer at least twice a year. Citrus rely heavily on micro-nutrients that are often missing from other fertilizers and soils outside of their native areas. Foliar feeding with citrus spray is a great way to supplement feeding in between major feedings. Don't fertilize while flowering as it causes fruit set to diminish. I do late spring, summer, and early fall, but for your area I'd say quarterly since you don't get cold winters like here.
3. Water less when not fruiting and more when fruit has set and has confirmed set fruit development. You'll know you're watering too much when the leaves get chlorosis, and too little when set fruit drops and/or leaves curl inward and look like green taco shells. Water even less during cooler months (though, again, with Florida you won't have to worry about that as much).
4. Monitor for sun scald. Citrus normally take full sun all day like champions, but variegated varieties can be more sensitive to intense sun, especially in the afternoon. If it becomes an issue, use shade cloth.
