Copy pasting from the old wiki is fine, as long as you review it. Consider writing new and improved articles if you're able to. A lot of the information in the old wiki is inaccurate, dated or simply irrelevant.
Avoid writing route strategies, instead focus on technical explanations on how a level or a trick might work. It's best to focus on stuff that doesn't change much over time.
YouTube video players are unofficially supported by some workarounds. Use a full youtube URL to make it an embedded video, and a short youtu.be link if you don't want it to turn to an embedded video, useful for links inside paragraphs.
Some of the glitches in the old wiki also use dated or weird terminology. For example, Collision Boosting or Brute Launching. These were taken from HL2DQ Tricks text, but in reality nobody uses these terms. Use the names used by the community instead, like slopejumping.
Half-Life 1, Half-Life 2 and Portal articles are welcome! Portal 2 is out of scope, since there is a separate Portal 2 Speedrunning Wiki