My biggest recommendation is to "Just Start"!
Whether you are doing FMQing or Straight Line Quilting,
it's all about ... practice, practice, practice ...
Don't fret too much if it is not as perfect as you want it to be.
Then ... practice, practice, practice ... more!
I'll agree with
ASabrinao to a point ... work with smaller pieces, but not too small.
At first I was doing smaller pieces and then discovered I did better with larger.
Why you might ask?
With a small piece you are running "off the edge" and having to deal with that constantly.
The more "Wide Open Spaces" of a 24" or 30" square,
gives you a chance to FMQ without running out of space.
Another suggestion ... Keep notes!
I keep a small notebook with the name of the project and date at the top of the page.
Then I list tension, stitch length/width, stitch #, thread kind/size/colour, needle make/size,
batting type and any other pertinent data.
When I do a similar project, I start with those same settings.
They may get changed, but it is a starting point ... and I note the changes.