Many healthy adults do fine with up to about 400 mg of caffeine a day (roughly 3-4 cups of coffee). Tea has less.
Watch out for
Sugar added to each cup, drinking late in the day (it can disturb sleep), and tea with meals if you are low on iron.
This is general information, not a substitute for medical advice. If you have a medical condition, are pregnant, or take regular medication, talk to your doctor first.