I can give you a very simple guide to necessary eps, at least so far:
- S2: "The Measure of a Man". Rare early classic and introduces Bruce Maddox, the cyberneticist mentioned last week re: Data.
- S2: "Q Who?" Introduces the Borg.
- S3/S4: "The Best of Both Worlds". Legendary two-parter. Picard, the Borg and a nearly world-ending battle.
- S4: "Family". Picard returns to his family's vineyard (which he has taken over in the new show) to recuperate from the Borg incident.
- S4: "Brothers". Data and evil twin Lore are reunited with their creator, Dr. Soong (also played by Brent Spiner).
- S4: "The Drumhead". Jean Simmons is a fanatical Starfleet prosecutor on a witch hunt. Picard must stop her.
- S5: "Unification". Two-parter with Leonard Nimoy as Spock. Picard and Spock work for peace with the Romulan underground. Key to Romulan lore.
- S5: "I, Borg". The Enterprise encounters a lost young Borg, Hugh. This episode will be very relevant to the new show.
- S5: "The Inner Light." Classic Picard episode.
- S6-S7: "Descent." Two-parter featuring Lore and Hugh. Also important.
- S7: "All Good Things..." The excellent Picard-centric finale.
Two movies very necessary: First Contact, Borg-centric and the only good TNG movie. Nemesis, terrible but very relevant re: the fate of Data.
Also:
Voyager elements will become relevant. VOY is a mediocre show with some good stories, but features heavy Borg lore re: Seven of Nine (Jeri Ryan), who will be appearing soon. Watch "Scorpion" and "The Raven" in S4, "Dark Frontier" in S5 and the series finale, "Endgame". If you're familiar with all these, my bad.
You're welcome!