Connecting the body parts and then tweaking it

Here I will be posting a screenshot of the female character base here (the normal background image) that I will be modeling

What are the tools and options used to connect the arms and legs and to tweak the shape that you wanted to be (The muscle of the arms and the breasts for her)

Although I didn’t make the feet yet so the arms and legs will come first

Also sorry about posting too many screenshots and I was trying to put only one ^_^;