Jeremy is absolutely right about resources in a firm. Capital is a huge issue.

One of the biggest issues a startup will face is the Built It/Buy It question. You need a new piece of technology or software to do business. Maybe you need a CRM, or a time tracking app for employees, or a document filing and stamping system. Should you buy a product already on the market or make your own? There's a lot of factors here that come into play such as speed to market and cost of development vs licensure.

Another issue that startups can run into is a lack of bandwidth. When you engage contract developers for work, make sure you discuss timelines and what their workload looks like. Is your team going to be dedicated to your project or are they working on other efforts. Hiring 1 developer to build something might seem like a great idea, but if they are working on 10 other projects, you might never get your product.

I hope this helps! If you have any other questions, please feel free to reach out!