A real person. Really! Playing a real opponent in long time controls is the best chesstraining. Then you analyze the game.
Study games. Some suggestions.
Bobby Fisher =
Tactics tactics tactics
''I do have some convecta software'' Always top notch (russian chess).
Endgames endgames endgames
Absolutely quite boring but not always.
Study the sicilian openings - buy books - look at annotated games.