What are some good gaming strategies for slither.io?

Slither.io belongs to my favourite browser games, even though I'm not a very good player of it. I tend to get eaten just when I get more mass and it's getting annoying for me, getting after 1/2 hours getting killed with 5000+ mass.

What's a good strategy to gain mass fast and then surviving for some time while big? That is, getting mass fast and not getting orbizized (killed)? All answers will be apreciated.