For ex: If I were showing the size of the social media market, and I have a tool that lets you schedule tweets - should I show a segment? Also, do I use a bar graph or show existing competitors and their % of the market?
I like to take a rule from the Steve jobs playbook and use simple circles... one larger than the other but no more than 2. your most immediate target (realistic reachable) and one of the "enemy" competitor company. or overall untapped market cap.
**for this to be effective you must provide as accurate projections as possible**
no bar graphs and as little or no text as possible... remember that a deck is a companion to the speaker... avoid bullet points and use the deck to entertain rather than educate... is not a class is a pitch. :)
Too much detail is a mistake - you want to convey an impression, not give detailed figures. A detailed graph distracts your audience from what they should be concentrating on — you the entrepreneur.
Also, more important to show change over time than how the market is right now.
You should have Market Size and Addressable Market.
Market Size you can display with a large number, and then include some logos of companies and their market cap.
Addressable Market you should include a number.
If you are raising money, it is suggested your Market Size should be in $Billions.
Use the graphical way that shows your startup in best way. If your market share isn't much then don't go for options like pie chart.