Using these tactics I can get over 5,000 almost every time I play within 1–2 minutes, regularly crest 10,000, and have touched the top of the leaderboard at least once a day. Of course, I die a lot with only 100 points, too, because of a bad turn or bad luck. The constant looming fear of death is what makes Slither.io a great respite from life's worries. Oh, I usually name myself "Don't Tread." If you kill me, let me know, so I can hunt you down in another life.
I've made it to 50k, so can speak with some authority when I say that even advanced players would do well to learn "The Cross" or, as we call it in Snakefleet, the Johnson Maneuver.
Previously: What if Slither.io was a text adventure