Good on you for being proactive! The customers and prospects who tell you about their bad experience are worth their weight in gold. For every 1 who actually tells you, there are scores more who didn't bother to tell you but had the same bad experience.

Having said that you can't take customer feedback at face value. In this particular case I would email the customer back and ask them specifically what she means by "boring". Ask her what else was off for her and also ask what she thinks you are doing right.

Hopefully, you also have some kind of analytics installed on the site so that you can get general statistical data in addition to case-by-case anecdotal feedback from users.

To answer your question - there are an unlimited number of things you can change to affect user experience and increase conversions. It all comes down to testing different tactics.

The most impactful things to test are site mechanics, UI and copy.

Mechanics is how fast the site loads, does it appear properly on all major browsers and platforms? Is it mobile ready? Does it rely on plugins that various browsers might not have?

UI or user interface is primarily concerned with making it super easy for a user to know where they are, why they are there and where they can or should go next in your site. If you have analytics installed and a decent amount of traffic each month you can begin to see patterns around bounce rates, exit pages, time spent on a page, visitor funnels etc.

Next on UI is aesthetics. I agree that you need a logo. You can stick with the same theme or change to a different one that might be more open and provide a better experience. You can experiment with colors however, do consult an experienced designer on that as some colors just don't go well together.

Copy is probably the biggest thing in the mix. Having good copy that pulls a visitor into each page and leads them into a sales funnel is the deciding factor in terms of conversion rates go.

If you would like to discuss details or specific tactics for any of this call me and I can get you going in the right direction.