Increasing Weight Without Changing BalanceSome players seek to simply make their racquets heavier without altering static balance. To increase overall racquet weight and retain the same balance, add weight in the throat, or 6 o’clock position. This will slightly increase swingweight, though, making the racquet a little less maneuverable.
They say if you put lead tape on the six o'clock position the balance point wouldn't change that much. But 30 grams is quite a lot for changing a racket's weight. One thing you have to know is that no matter how you apply lead tape, and no matter how close you get to the desired weight, you still wouldn't end up with another racket; otherwise they would only sell just one model, and let us put lead tape to make it into different models.
The packaging of the lead tape(s) you buy should tell you how much weight it is an inch, e.g. 1/2 gram per inch, so 30 grams of lead tape should be very long, not just "2-4 pieces". However, you can stick one little piece on top of another at the 6 o'clock position you'll put them on. Some people, like Sampras sticks several layers of lead tape at one position of his racket. Some people say they like making each layer slightly shorter than the one below it so that you can see how many layers you've put on.
Leading up 30g using lead tape is not that practical. As Leiya_206 mentioned, the ordinary kind of lead tape in the market is spec to 0.5g/inch, for 30g you are talking about 60". You can imagine how can you piling up to put it on. So, the way, I am doing is injecting silicon (some racquet customizers using injection foam) inside the hoop, but it is quite a big "operation".
Since, you would like to keep the balance, then the whole 30g has to be scattered applying from the butt to the tip of the stick. Also, injecting silicon is not as direct as lead taping, you have to be sure and do all sort of pre-calculation before applying. As you have to know once silicon is injected, then is a no return.
Another major area that you have to consider, is once you add 30g, even keep the balance, the swing weight will increase dramatically. If I remember it right, the swing wieght of the O3 White Sharapova is already 320+, if after adding 30g keeping the same balance, I guess the swing weight will be close to 340 (depends on where you applied the weight on the hoop. For 340 swing weight, which I think is not that suitable for lady player, my LM Prestige mid swing weight is only about 345, which I also feel harsh sometime when I am not in condition.
I suggest you really have to think whether you really what to do so, or consider switching to another heavier stick.