1. Most of us have a pretty good idea of what is right and what is wrong - it sort of is part of us. Jesus tells us that following his way is the right thing to do. Jesus always looked to God when tempted - he prayed and he remembered bits from the Bible. We can do the same.
2. If you think something is wrong - there is probably a reason you are thinking it; it probably is. Talk to someone about what you are thinking about and try to work it out. Remember that you want to do the 'right' thing - try and work out what that is. It won't be hurting someone for sure, and that includes hurting yourself (e.g. temptation to ditch the homework only leaves you not knowing something!).
2. The thing is that wrong thoughts (or as the Bible often calls them, evil thoughts) begin as thoughts, but then if we keep thinking on them they can grow to actions and actions if repeated become habits and habits if not dealt with become our personality.
Created with images by Agence Olloweb - "Il s’agit d’une photographie réalisée pour illustrer notre page des offres de création graphique de l’agence web Olloweb Solution" • Aaron Burden - "Cross during sunset"