First new post in two years. This is just a short one to hopefully break the ice.
Today, a friend introduced me to a smart young business guy looking to get into the startup world. This is the advice I gave him.
Of course, the best way to break in is to start your own company. Even Y-Combinator has begun accepting fairly non-technical people from business schools as part of teams that also have some technical chops. In reality, many people don't want to go this route, or don't feel comfortable with it and want to get their foot in the door as an employee first.
If this is the case and depending on your resume, I think the best plan right now would be to either join a small company more on the order of 10 employees in general marketing, or join a larger startup company in sales or finance/accounting.
In either case, the goal is to find a way to add tangible, unique and valuable work product.
In a small company, marketing is kind of a catch-all for everything that is not writing code, so there are a bunch of different things that you can do to help out.
I would actually look at sales or accounting more closely. The goal here is to put a succinct example of quantifiable success at a successful company on your resume. For example, if in 6 months you could say: I was the top producing rep at Twitter or Box.net or Yammer or something like that, then you'd have a really good story to leverage into other more interesting jobs. Additionally, right now enterprise SaaS companies are a really big deal and repeatable sales success is their biggest problem, so I think that now is a particularly good time for sales to be an entry-point.
On the finance/accounting/risk side, I think that there are a lot of jobs, but not too large a pool of qualified applicants in the industry. For instance places like Zynga and Square have a lot of need for these people, but I have only ever met a few people in the industry who do this.