1. Change text, specifically around your value proposition. Emphasize different things and see what happens.
2. Remove content. Make the page more focused on what's important. Here's an example that increased account creation by 43% at Optimizely: http://blog.optimizely.com/2012/10/09/optimizelys-100000th-e...
Based on this article, only larger changes should be done by smaller startups. But smaller startups have less resources to throw at larger changes. I mean, what of we're not planning on redesigning our web page?
That said, the kind of results startups could get by tests are usually obvious at the balance sheet (or some other big metric) anyway, without any kind of formalization. If you have one of the rare situations where it isn't, go ahead and do a formal test, but I wouldn't recommend anybody to lose some sleep over it.
For example, a startup not testing small changes right? Well unfortunately, an entire landing page makeover, while not overly difficult can windup taking a great deal of time. The redesign alone is just such an "opinionated" process (even by people who know nothing about design...) that throwing that much investment just to test is hard to justify. So even though most startups shouldn't waste time on stuff like button colors...that's often the only thing they'd have time for.
Of course I'm talking about the smaller scrappy startups. Not the ones backed by prolific amounts of capital.
Don't get me wrong. This is a GREAT article, I just would like to know the best level of effort for ab testing for the smaller guys.