Hello - Thread tension is a significant issue for anyone. You can check your thread tension with the zip file that is in this blog - The Avid Embroiderer, Needles. There is a lot of good information (IMHO) that will assist you. If you have been fiddling with the tension, it can make a nightmare for you. Work with the test and use old throw away clothes to practice. Use up some of your fabric stash for these times as well.
I am uncertain about a portion of a design stitching out but then in another section it is a problem. That is unusual. One thing that comes to mind is a poorly digitized design where there is too much stitching which creates cast iron stitching. That will cause fraying and thread breakage. Try other designs. Work with simple ones and work your way toward something more complex.
I think (IMHO) that when starting, too many embroiderers try out something that is beyond their capabilities. We all want to do something spectacular but the fact is that no truly talented person begins at the top.
My second suggestion is that you work through this Forum project: http://www.annthegran.co...ms/p/1218/5460.aspx#5460 (it is at the beginning of the forum.) One needs to be able to successfully do some projects and gain confidence to go on.
My last suggestion is to read, read and then read some more. Not everything you read is accurate, but you must try some techniques on your own because various issues can make your results different from mine. For instance, I live in Southern California. The humidity is low here. Thread, stabilizers, fabric and machines can act differently if you are living in southern Florida.
Make sure you are using a good stabilizer. For newbies I suggest that you get a medium weight tear away for general play and learning experiences. A stabilizer can make or break a project.
Ask questions, this forum is particularly good and loaded with talented people. This time of year, we are all busy, so do give us a chance to respond to you. Then - - read some more.
Pat, The Avid Embroiderer