conversion rate

In terms of what leads to a sale, my top three would be:

1. Serps Position
2. Title tag
3. Price

Theory being price is least important because anyone diligent will do price comparison, while the other two together will sway a good chunk of the searchers.

Thoughts or additions?

-Greg

I'd say a good website design is necesary. Even if you do have a top position, if your website looks like crap, or has broken links, you won't get many sales...

the key for higher conversion is to attract users they're close to make a purchase.

well duh. I'm talking about breaking down those last finally few percentage points.

I agree with dejaone, it is all about timing. I know someone <sigh>looking into the air</sigh> who operates multiple sites selling essentially the same products. The only diferences are the site layout and price. The more expensive site will outsell the cheaper site some months. It is really about timing more than anything.

So, using your list, I would say SERP's results would be my highest priority...I want to be in as many people's faces when they are looking to buy something now.

Greg, your order and priority are correct. If I were to add something: 3A. Provide higly relevant and enticing content and ensure the visitor is no more than 3 clicks away from the purchase decision. 3B. Price

Statistics show that most sales are lost soon after the visitor first decides to buy. Don't want the visitor to have to search or click too much in order to make the purchase. I lose 60% of potential customers at the credit card page, but that is about average. There are a multitude of reasons why, e.g., security concerns, just doing a pricing check, cold feet, etc.

I agree with SEO_AM. A lot of visitors are scared of using there credit-card online. I have had my credit-card information stolen after making a purchase online. Good thing I checked my statement online that night and noticed a charge that didn't belong to me and cancelled the card right away.
Yet this right here:
"3A. Provide higly relevant and enticing content and ensure the visitor is no more than 3 clicks away from the purchase decision."

Is the most important factor. You have to sell your product before you actually sell it. You're going to have to have the customer thinking he needs your product and then you will have a better chance of getting sales.

very good point. and it goes to the issue of usability for sites in general - you shouldn't have a complicated hierarchy.