Just in case I will post this.

When I first tried taping I though you could do the whole job just once and be done.  No.

First a thin layer of mud, tape. Press tape into mud.  Let dry, maybe 8 hrs or over night. 

Come back knock off all pieces of mud that are sticking up.  Making the wall smooth again.

Apply mud again and this time use the wider knife, maybe 12 or 14 inches and try and get it flat.  If you are good you can get it done this time.

If not let it dry again, repeat until you get it smooth.  Sponge smooth or sand smooth.