I suggest that you consult with your dentist
before considering any whitening regimen.
Generally speaking, the modern approaches to tooth whitening
are safe and well tolerated. There is a common mis-perception that tooth whitening causes destruction of enamel, but this is not the case. Older whitening regimens did damage enamel, because they essentially required scrubbing of teeth, and the mechanical friction could damage enamel. However, modern whitening approaches are actually bleaching agents, which simply get into the pores inside the tooth structure and remove the stains that have collected there.
The main side effects of tooth whiteners include increased tooth sensitivity and some irritation of the gums if the whitener gets off the teeth onto the gums. For these reasons, it is worth talking to your dentist to make sure you have generally healthy teeth and gums, for which this irritation and sensitivity are not going to be a major issue.
Also, your dentist can give you advice on what tooth whitening procedure is right for you. Generally speaking, over the counter whitening products are less effective than products applied by your dentist, but they may be right for you if your stains are minimal.
Start by talking to your dentist!