I've created a script that helps automate this issue.
It is based on my complete answer 22 in a question very similar at stackoverflowstackoverflow.
You can read all the explanations there. To summarize I would recommend just SIGTERM and SIGKILL, or even SIGTERM, SIGINT and SIGKILL. However I give more options in the complete answer.
Please, feel free to download (clone) it from the github repository to killgracefully 1