I have been embroidering for just over 7 years. I was generally self-taught and I started without a clue about machine embroidery at all. Over that period of time, I have been learning by trial and error (make that trial and frustration). During the past year, I have been fortunate to meet a good instructor whose group that meets regularly in my area. I have been able to learn correct methods of embroidery; and, have had to unlearn some bad habits.
These are my thoughts on things I wish I had known when I started. I am sure you will recognize some and have a few of your own. Please share your thoughts too and we will smile at the naiveté we once had.
Your initial investment of a machine is just the beginning. Just like any craft, there are multiple items that you will need for your arsenal. IHMO, the second biggest investment will be in the special thread required. But you need designs, fabric/other platforms to embroider and appropriate needles, scissors et al.
The User's Manual for your machine's data and guide. Look at the Chapters (front of book) for items that interest you. The whole book is too much to take in because it is unfamiliar data. After you have played on your machine, you will want to read specifics you encountered. Keep the guide close and refer to it often. Use your machine as the company created it to be used.
2) I am computer savvy (taught software for 5 years) I can make a program to organize my designs
a) After all the hours I put into this, I still don’t have a picture, size and other important information for my designs. 
b) Good and simple software for ME was hard for me to find. Catalog Express is ME specific and insightfully user friendly. Everything I need to have is at my fingertips. (I would never recommend any item I deemed to be second class.)

B) MATERIALS:
1) I have thread, needles and stabilizers already
a) Specialized materials are necessary to achieve desired results.
b) Not only did those old materials not measure up, they would damage my equipment and cause me frustration.
c) New and more inventive materials are being developed constantly.
2) Joe’s Thread and Used Tires has a great deal
a) A quality thread in ‘best seller’ colors is a true bargain.
b) Quality thread often comes in exceptional storage containers helping us stay/get organized. [Photo below courtesy of Madeira]
(ATG carries the Thread Treasure Chest in White or Teak)
c) I personally purchase here at ATG because quality is of utmost importance to me.
C) Learning Curve:
1) I can learn from a few lessons and the book provided by the manufacturer
a) The book only shows the technical aspects of the machine.
b) Lessons were actually inadequate from my dealer.
(1) I would be learning with every project.
(2) I ask questions and answer some others as well.
(3) I discuss and listen to experiences from users worldwide.
(4) There is always some new technique to learn.
(5) I keep notes on my computer (and use “favorites” at ATG-mark by clicking on "Favorites" in upper right corner of post, retrieve through your profile) on forum discussions, sites, lessons learned and possible resources, etc.
2) I can figure this stuff out, I have been sewing since I was 12, I will just work through any issue. I got "A's" in Home Economics.
a) Computers and their associated items have traditionally become obsolete in a brief period of time, and ME has the very same time frame.
b) Innovations are coming available all the time.
c) Keeping up to date will be an unending journey.
d) Learning keeps us young.
D) Alphabets versus Fonts:
1) They sounded the same, so I bought Alphabets only
a) Monogramming is only a single facet of ME.
b) Placing words or phrases requires a ‘keyboard’ style of fonts. Alphabet Xpress is very easy and versatile in this function.
c) Monogram and words need to be in a large variety of styles and sizes.
d) Professionally designed monograms come in so many motifs such as floral, bridal, sports to name just a few. I don’t need to reinvent the wheel.
E) Machine Embroidery’s Place in my life:
1) I sure hope I get enough usage of this machine because it was so expensive!
a) ME is an addiction which I am delighted to have.
b) ME has a uplifting and honorable place in my life.
c) ME is a joy. I cannot draw a straight line, but I can create a lovely keepsake for each of my grandchildren.
2) This is going to take over my life and I will become a recluse-
a) I am so thrilled to have found so many new friends with which I have so much in common.
b) There are so many thoughtful and caring people who make my life even more fulfilled.
c) There are wonderful people in the ME community who make me laugh, cry and make me jump up and down with pure joy.
I suppose that few if any of us researched, prior to purchase, what ME really requires. In the earlier days, where would we have found information anyway? I think many of us saw a machine sewing away, got excited and the purchase was a forgone conclusion. Computers have turned the world of embroidery delightfully upside down.
Excitement is what this craft is all about, catch it!!
Next time, Needles Make Things Happen.