Time for some sheep theory. I'll start the ball rolling with some general ideas. Feel free to chime in.
1 Recency über alles. Nobody remembers Frank Sinatra or Marlon Brando anymore. Stick with current popular culture as a rule.
2 Chewbacca abuse. Chewbacca rule is misused 10 times for every 1 time it's used correctly.
3 Learn the memes. Yes, it might be better without the memes, but that won't help you win. Know the memes, but also know they evolve and change over time.
4 Connected answers. This isn't quite as prevalent as it once was, using similar answers on consecutive questions.
5 Think USA. Like it or not, POG sheep is dominated by Americans and American thinking. Factor that into your sheep thinking.
5 Use the mod. If a question asks for a pogger, use the game mod.
I like to enter early so I can think at my leisure, and so I don't forget later. I try to go with my first instinct, but I also try to keep an open mind as I recheck my answers. Miss an easy sheep and you're toast.
No research is funner and easier, but research can sometimes be crucial. This is assuming standard sheep rules that permit research.
Run your own games. Seeing how people answer your questions helps you understand how sheepers think.
Also count your answers before you send the PM to make sure you have exactly 1 answer for every question. Doublecheck.
If a single answer hits you within 3 seconds after reading the question, go with it and don't rethink it.
And #4 in the OP is virtually dead in my recent experience. Only apply it to super level 1 obvious connections, or maybe to decide between a 50/50 answer. Otherwise disregard.