Talk to your LD about what he/ she wants.
Theater:
Usually you would spike all the furniture/ scenery items in their places for each scene. (I usually use larger marks and label them, larger than I would keep for the scene shifts, but something very easy to find during focus). You can also lay out lines for walls/ scenic items that will not be present for focus. (Use the measurements from the groundplan/ your rehearsal set up).
You should also give a DS center mark, center-center mark, US center mark. Maybe the LD will want a full line running from DS to US at centers and quarters. Check w/ him/ her.
You can also mark the location of any specials that you might know of. (Don't go crazy with this, lest you step on people's toes) But if an actor always delivers a speech at a very specific location, it can be helpful to mark that for the designer.
Dance:
Mark centers and quarters and eights (US, MidStage and DS). Make lines from US to DS at center and quarters (for boom focus).
Mark any specials for the pieces you will be doing.
In all circumstances, it is best to chat with your LD and find out what his/ her needs are. You should also check with the director. Perhaps he/ she will want to confirm furniture placement on the stage before focus. (If you rehearsal room is smaller than the stage, this will probably need to happen).
Good luck. Just remember to make the marks obivious and easy to read. You should re-spike later for scene shifts, preset, etc.