#1: You should expect a bit of a different experience than seeing a psychic face to face. First of all, one of the big advantages of online readings (or phone readings) is that they are "blind". The reader can't see you, and therefore can't make a lot of assumptions about you based on appearance, dress, age, or body language. (all things commonly called "cold reading" by skeptics, and can happen even to the very BEST and well intentioned readers by accident, simply due to human nature)
With the additional layer of anonymity provided by online chat or telephone readings, you should expect, and allocate a few extra minutes for the reader to settle in and "feel" your energy and pick up on your aura. While some psychics will tell you that they felt you and knew your issues before the reading even begins, in my experience, the vast majority of the time, there is a 3-5 minute "energy exchange" that you should expect. (and want for accuracy and intimacy)
#2: You should expect far better guarantees and performance promises online, or by phone, than you'd find in the "real world". As a matter of fact, in my view... this is one of the very best reasons to get a reading by a service or network, over seeing a local intuitive, medium or clairvoyant.
How so? In my 15 years or so of researching this field, I have never, EVER asked for, or seen someone else ask for and GET heir money back or a refund after getting a reading they weren't happy with in person. In other words, sitting face to face with someone... even if the reading is terrible, you are far more likely to walk out and be disappointed, than you are saying... "hey... that was bad and not accurate. Can I get a refund?" It's just not the way the real world works.
Online? Due to the performance promises and money back guarantees many of the biggest psychic services offer, it's much easier, less confrontational and quite simple to say - "not impressed. Would like a refund."
That said, you should take advantage of this liberal policy, and only hire psychics (or services) that offer world class customer service policies to protect callers and clients from bad or disappointing experiences. You should also expect to pay about HALF for an online reading than you'd pay for a comparable reading in your local community, or even less from a well known celebrity psychic.
Lastly, you should expect a fun, memorable, entertaining and enlightening experience. Don't settle for less... as a good reading should be ALL of the above, and more. (and if you are stuck and need the help... you deserve nothing less!)