In your first meeting you need to solve the VC's big issues.  It's likely that before (or during) the first meeting the VC will have identified several key concerns that could end their interest in your venture. These could be the competitive threat, the addressable market size, the likelihood of acquiring partnerships or a variety of other topics.

In that first meeting VCs will try to understand those topics well enough to determine whether or not to continue evaluating your company.  It's usually pretty easy to figure out which issues the VC is most concerned about. Tell tale signs include lots of questions about a topic and/or concerned facial expressions.

When you are managing the pace of your presentation, be sure to allocate more time to these topics. Make sure not to move on to other topics until you have done everything that you can to get the VC on board with your perspective about these issues.

If you find that multiple VCs get hung up on the same issues and you can't convince them that their concerns do not present a significant challenge for the business, you should consider the possibility that they are right. This could be an indication that there is a problem with your current model.  Take a step back and try to innovate - create a solution to the big issue before continuing to meet with other VCs.

If the problem is truly intractable, it may be that venture capital financing is not appropriate for your business. Many great businesses have been built without venture capital financing; venture capitalists focus on a specific type of investment opportunity, and a minority of private companies fit this profile.

You won't be able to get every VC to see your vision, but you should always do your best to solve each VC's big issues so that they can get one step closer to believing.