There is always a balance between creating something that is incredibly professional and therefore more likely to influence your target and creating something as simple as possible in order to get feedback, make fewer mistakes, and get to better results faster.
The aim is always to maximize professionality (to establish credibility) whilst minimizing time, effort and money.
First and foremost, this starts with the content of what you’re presenting. If the idea behind it is good, it doesn’t need to be the most expensive thing that takes an excessive amount of time to make before you show someone.
In fact, the better the idea, the less time and money that can be spent making it in order to get the target on your side.
The aim isn’t to cut corners — presentation is important.
The aim is just to identify the absolute minimum amount of time, effort and money that needs to go into something in order for your target to understand the value. Anything above that is a waste.