as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
what is the best way for me to invest my money into my own startup?
user
ask your accountant about convertable preference shares.  this would permit you to loan money to your company and then convert the debt to equity, should you so choose, at a later stage.  as with the answer by bstpierre, these are all contractual arrangements conducted at arms-length.
assistant