I know a lot of people are offering advice and I may not have anything to say that they don't but when I started on ebay I read a lot of things and it really helped.

I started by selling my own stuff to clean house.  I really enjoyed it. So I have learned some things the hard way and hope to help someone else get started as well:

• take it slow and don't expect to make big bucks (if you do, write a guide for me, please)
• buy and sell personal stuff for a couple weeks to get a feel for how ebay works
• sign up for PAYPAL immediately. you get your money fast and safely
• FEEDBACK is very important and you gain yours as you do the second step
• answer people's questions as promptly and truthfully as possible. They will remember that and YOU
• if you make a mistake, admit it and make it right, even if you eat the sale. They also remember that and YOU
• start going to garage sales, thrift stores, etc but be careful and pay as little as possible. Unless you know what it is selling on ebay for, you may be putting out money you will not recover
• start a separate checking account....just a "special" account is fine. Don't go all out for a business one with it's expenses
• if you do this for several weeks to months and really want to make this a business or time-consuming hobby, open a basic store.  It will take a lot of time getting around, setting it up, making it look like you want. You will spend a lot of time on ebay and you need to make that commitment right away if you are going to make it any kind of a business.
• UNLESS YOU ARE RICH, DON'T QUIT YOU DAY JOB. you now have 2 full-time jobs but it can be worth it
• I learned the hard way...don't jump into another WEBSITE.  costs money, takes a long time to get the search engines to find you.  You CAN get a domain name like John.com and then reroute everything back to your store.  Your keywords will help John.com get noticed but get some more advanced advice about it
• this is not a get rich quick thing.  Don't expect it to be.  A business takes a long time to really establish and make money.
• realize that during the summer months, everything is slow. If you have the capital, and depending on what you are sellling, haunt the sales and get some things for when you need the inventory when things are busy
• LASTLY, GIVE YOURSELF A BREAK.  YOU ARE LEARNING A NEW JOB!  IT TAKES A LOT OF TIME AND PATIENCE (WITH YOURSELF).
• have a good time and may God bless all your endeavors