Listed in no particular order: * Learning tools (they get in the way of solving the problem at the beginning imo) * Incomplete/inaccurate documentation * Not

Listed in no particular order: * Learning tools (they get in the way of solving the problem at the beginning imo) * Incomplete/inaccurate documentation * Not knowing what things are possible (both in code a la standard libraries or language features and working with tools like debuggers) * Not knowing simple best practices until you're bit by something and find them out through a slow, painful discovery process