A venture capitalist is charged with finding a relatively small number of investments (usually less than a dozen per year) to make over a 7 - 10 year period. While the venture capital firm may look at thousands of deals in a given year, they can only pick a handful of deals to pursue.
Writing Checks is Easy. Managing Companies is Hard.
The reason venture firms can only make a small number of investments is because each investment must be personally managed by one of the Partners of the firm. Since partnerships tend to be small - less than a dozen partners - the number of venture capital portfolio companies that they can reasonably manage is also pretty small.
Therefore you're really competing for the venture capitalists' time, not just their money. They can easily write more checks, but they can't allocate any more time. They need to be sure that your investment is worth segmenting their time even further, reducing the amount they can spend on existing investments as well as new potential investments.
Know Their Focus
Investment deals are complicated, and unlike public company stocks where you can judge a potential investment based on numeric values, an investment in a startup company can only be gauged based on how well you understand the sector that company is in.
Be certain that whomever you are meeting with understands your industry. Don't assume for a moment that because they "know about business" that they are the oracle of every industry. Venture capital Partners to be highly focused on particular market segments where they have a great deal of domain expertise.
Your best bet when selecting venture capital firms to pitch is not only to find out where the firm tends to invest (you can find that in their portfolios) but also where the particular Partners within the firm invest. You'll get far more traction with a Partner who knows and likes your industry than one who will spend more time trying to figure out what you do rather than why you're special.