I've never played your mud, but some tips:

1. make turning the ascii map (if you have one) off easy; maybe with a question during character creation.
2. avoid areas with many locations that all have the same or similar names, and make sure many of your locations have unique landmarks. This makes it easy to give instructions to players who can't see the map: "go three south of the large tree in the center of the woods then west." Muds with 10 or 15 hunting areas all called "woods" "dark woods" "northeast woods" etc that are all the same are hard to keep straight without a map, and most blind players won't have a map.
3. If a recall or teleport function can fit into your game, put it in.
    That way, when a player becomes lost, he can recall to the starting location and try again.
4. Warn players when they are approaching a maze. Mazes can be fun, but it could take a blind player an entire afternoon to map one small maze (remember: he can't use your builtin ascii map for help). If the player is aware that something he needs to progress is located in a maze, or that he's getting near one, he can either avoid it and decide to come back later when he's got more time, or ask another player for help getting through. And for the love of God in heaven, mazes with npcs that transport the player to another random location in the maze, or steal worthless objects the player was using to help map the area, are not fun! I saw a maze with both these things in a mud, right near the start of my game, and I left and never went back.
5. allow players to change the prompt. Most muds have way too much information for screen readers on the prompt by default.
6. allow players to turn off the mud chat network/chat channels/whatever your mud calls them. One nice option, that I only ever saw on one mud, was "suppress chats during combat". That way I could leave everything on, but not get spammed while I was doing something I needed to give my full attention.
7. give instructions to get to some important mud areas in your newbie guide. In a perfect world, these areas (about 5 or so) would be spread out through your mud, so that a player could have several good places to start exploring and getting to know the world.

Those are just some ideas! I'm sure other players can think of things I missed, or disagree with some of my thoughts above.