Even though it may rain buckets from the heavens, you still need to water pots and containers of plants. Terracotta is especially prone to moisture loss, especially if exposed to sunshine or wind. Clay pots should be checked daily to make sure the compost is moist, and most containerised plants (although not alpines or Mediterranean herbs like rosemary and thyme) should be fed weekly with a liquid feed. Alternatively, you can use a handful of pelleted chicken manure two or three times during the growing season. Slow release fertilisers - like Osmocote - may also be used, but be sure to follow the instructions.
Meanwhile, get into the habit of looking closely at plants. Many pests and diseases can be nipped in the bud by simply removing the offending creatures or cutting out the affected part. And, in the case of variegated plants, where you see plain, green shoots, cut them out immediately; these will soon overwhelm the entire plant.