If you were among the millions expected to shop online on Cyber Monday, you had a hand in bumping ecommerce sales over last year's, some preliminary data is showing.

Though final statistics for the day's traffic and sales are not yet out, PayPal reported as of 11 a.m. Monday seeing 196 percent more mobile payment volume compared with Cyber Monday 2011. PayPal expected to update its blog at some point today with a full recap of Cyber Monday numbers.

On Black Friday alone, not typically know as the biggest online holiday shopping day, ecommerce sales jumped 26 percent over the previous year and passed the $1 billion mark for the first time, according to ComScore Inc., which tracks digital business. ComScore was expecting Monday to be the heaviest online shopping day of the season, with a projected $1.5 billion in retail ecommerce sales.

A study released earlier this month shows consumers are still doing most of their online shopping on laptops and desktops -despite the rise of tablets. Apparel and books are the top online categories and Amazon.com and Walmart.com are the most frequently visited sites, The Adcom Group study says.

UPDATE: Walmart.com announced late Tuesday that it had its best day in history on Cyber Monday, with strong performance from mobile sales.  The retailer said it plans to offer Cyber Week specials though Sunday, as well as free shipping and free in-store pickup on more than 100,000 items throughout the season.

The Adcom Group study found that shoppers browse more than they buy and often find the online experience frustrating. More than half of those surveyed said they had problems buying online, with about three-quarters abandoning an online cart because of that frustration.

To reduce the frustration -- especially to ensure getting holiday deliveries on time -- consumers should be sure to read the fine print about shipping time-frames and delivery cutoff dates, said Ethan Giffin, CEO of  Canton-based ecommerce company Groove Commerce.

Giffin, whose company builds and implements ecommerce sites, also recommends making sure the site is legitimate and checking that the payment system is secure. That's especially important with unfamiliar sites, when shoppers should look for assurance and security  certificates and make sure a contact phone number is available. Consumers should also be wary of sites that ask for personal information other than credit card and address.

And as always, buyer beware.

"If it seems too good to be true, it probably is," Giffin said. "It's important to feel comfortable with the overall feel of the site."

lorraine.mirabella@baltsun.com