I don't have a specific favorite technique but for cold outreach, I really like Evaboot's RABT method. It really helped me grasp what a cold outreach message should look like: https://evaboot.com/blog/linkedin-inmail-best-practices
RABT method:
• Reason for outreach
* Explain clearly why the conversation is relevant for your prospect.
• Ask a question
* Ask a question to know if your prospect has the problem you solve.
• Back up with data
* Back up your question with data to show you have done your homework.
• Tease a solution
* Show that your solution is able to solve the problem but don't say how.