"It is also a good idea to improve my communication skills. And in this way, I can make more friends, which is beneficial for my future development."
It's all grammatically correct, but it sounds a little odd. I would replace 'And in this way' with 'In doing so'. Otherwise, beneficial for my/our future development is correct.
NOTE: If you want that the benefit is for you instead of your DEVELOPMENT, you would replace FOR with TO. So, 'it is beneficial TO me/us. So you use FOR when it's a noun and TO when it's a pronoun.
Hope this helps! :)