netmeg - 7:30 pm on Jun 17, 2011 (gmt 0)
There's a bunch of things I look at.
First of all, I like to compare apples to apples, and even if the products aren't seasonal, I'm more likely to compare April to last April than April to March.
Ok, so sales are down. But WHAT precisely is down? I had a client come to me complaining that his sales were down since he redesigned his website. We took a look at the analytics, and guess what, his number of sales were way UP, his conversion rate had more than doubled, but his sales DOLLARS were way down. Working backwards, we figured out that the dollar value of his average sale was a little bit more than half of what it was last year. Why? We're still working on that one. Bad economy, obviously. Also he repackaged some of his products - instead of qty 500 to a case, he's now selling qty 100 to a box - so people are buying more boxes. There's more to it than that, but you see where I'm going with this. Figure out exactly where your dropping and by how much, first.
Then you want to look where your traffic is coming from. Take a look at your top keywords for this year and compare them to your top keywords for the same period last year or the year before. Are they the same? Any big changes, plus or minus? Are you suddenly ranking for some really broad search term, or something ambiguous? I get tons of bursty traffic on a small niche affiliate site a couple time a year because the New York Times uses something I rank for as an entry in the crossword puzzle. Talk about useless traffic!
Under the content section, do the same thing with your pages - are the same ones popular this year that were popular last year? Learn to use the advanced segments, so you can get more information about how different types of visitors are using your site.
Do you have ecommerce tracking set up in your Google Analytics? And goals? If so, take a look at the sales funnel. Maybe people are jumping off some place in your shopping cart, indicating you have an obstacle there you didn't realize. Shipping too high, too cumbersome to add the shipping address, could be anything. But you want to look at that.
Personally, I wouldn't worry about doing PPC until you've figured out how to work your Analytics info like a mofo.
There's a ton of Google Analytics resources out on the web - and I'm pretty sure there's gotta be a Dummies book though I've never seen one. But a lot of your answers are in there - you just have to figure out how to fish them out.