Don't spend too much energy rationalizing your desired outcomes; they may be unrealistic. Actively challenge yourself to reexamine your assumptions as you're presented with new information to make sure you're not being overly optimistic or pessimistic. Otherwise, you may lull yourself into a false sense of security.
When considering how to mitigate risks inherent to a deal, it's important to think about how the world will change around you. Many of your obstacles will be outside of your control. So, don't expect them to resolve themselves and don't use them as excuses. Be creative and devise proactive solutions.
The pessimist complains about the wind; the optimist expects it to change; the realist adjusts the sails.
In the absence of perfect information, an educated guess is preferable to blind intuition. Pragmatism will help you seal the best deals.