IMO, if you’re working in Inform, the biggest thing you can do for newbies is to highlight objects and exits in the text in bold.
It is wise to ask players at the start of the game if they’re new to interactive fiction. When players self-identify as newbies, start by teaching them to “look.” (Just don’t display the description of the first room, and instead display a suggestion that the player type “look.”) Then, when they “look,” include a suggestion to “examine” one of the highlighted objects.
When they examine a carryable object, suggest that they “take” the object, and suggest “verbs” to display a list of verbs. (Ideally “take” will be their first verb.) When they take their first object, teach them to use the “inventory” command.
When they examine an exit, suggest “go”.
If you want to have an extremely newbie friendly game, use Aaron Reed’s Keyword Interface extension. Here’s an example, an excerpt from Blue Lacuna.
The next big thing to offer to help newbies is a map. A PNG map outside the game is fine; be sure to mention the map in your in-game help. I recommend designing your map in Trizbort or trizbort.io.
And the last thing to offer is gradual “invisiclues” hints, not just a walkthrough. The very best version is an in-game hint system that automatically provides context-sensitive hints when the player types “HINT,” but that’s a lot of work. Much easier, and almost as good, is a link to a forum post here on the forum with [spoiler] tags. We discussed this here: IFComp walkthrough best practices - #19 by dfabulich