I tend to be a naturally cautious person, and personally play my shamisen quite quietly, yet I feel like a lot of the shamisen sound comes from not being afraid to strike the strings somewhat hard.
I am just curious how you guys feel about finding the balance between technique and not wanting to break strings (or the Kawa.)
That’s a good question. It also partially depends on the shamisen you have. If it’s a shamisen built for tsugaru style, the skin will be thick enough that you won’t have to worry about breaking it. In the end, it really depends on personal taste, I feel. Some people tend to gravitate to an aggressive style, and so will want to strike the skin more forcefully. Others are quite the opposite, and will want to strike more gently. Both cases are perfectly fine, and you can exhibit good, intentional technique either way. 
On the same hand, I have a friend who was somewhat ‘pressured’ into playing tsugaru style. She was always attracted to kouta/jiuta styles of shamisen, but the only people around were tsugaru players, so she forced herself to play that style in order to get involved with other players. However, it never felt that natural or comfortable for her, and I believe it was just because she was naturally drawn towards a more gentler style than tsugaru. Recently, she’s rediscovered her love of kouta/jiuta styles, and is finally pursuing that.
Moral of that story: The shamisen is a great instrument for self expression. Just start playing the shamisen and try to get a feeling for how much power you like to use. If you find that you like to play gentler, play that way. If you like to play harder, that’s great too! (This is assuming your shamisen skin is sturdy) Playing how you like to play is the most important for emotional expression and connection to the shamisen.
Hello
I totally agree with Kyle.
In the beginning I tended to gently strike the itos and kawa of my tsugaru-shami; maybe more in respect to neighbours and lack of playing-knowledge/techniques.
Over time, while regularly listening to all kinds of shamisen music (being passionate about jap. trad. music in general), but especially tsugaru-style here, I really dug that snappy, percussive & entrancing sound…therefore had to find some other place for practice.
Since then I got hooked - addicted you might say - playing loud. For me playing tsugaru-style is also some kind of stress-relief and work-compensation, thus striking hard most of the time.
Still, after 1 year, the skin doesn’t show any kind of wear yet (w/applied bachigawa); only the ni-no-ito broke once and had to be replaced. I wonder myself about the san-no-ito still being intact, although striking it without merci 
So I encourage everyone on the one hand being diligent to their beloved and valueable instrument, than again play the instrument the way it is intended to be played in the first place.
Cheers
Ale
I agree with both Kyle and Alessandro! I’d also like to share my experience and bewilderment during my development as a Shamisen Player when I realized that the power and loudness of Tsugaru Shamisen is actually a result of “less” effort on the part of the hands, arm, shoulder etc… Rather than striking “Hard” (which almost always results in a crappy tone) . The big revelation came to me one day when I realized it is all about using the natural weight of the Bachi in connection with the earth’s gravity and literally letting it “Fall” into the strings. Keeping your hand, wrist and arm completely and Totally Relaxed until the very last split second (the TO of Chi-To-Shan) and even then utilizing it primarily to put just enough pressure to snap off of the strings. I was Amazed when it struck me (no pun intended) that the less forcefully you strike the strings, the more Powerful the resulting tone.
I can agree with all the preceding adding two observations. First, while “technique” would seem to be the primary goal, do let emotion fill you - there is no motion without emotion. Whatever the mysterious mechanism, emotion will inform technique. Also, for me shamisen is as much a percussion instrument as anything else; drumming can be good practice and help you feel Kevin-san’s gravity.