honestly, i was terrified. it took me like 5 years to actually quilt one with free motion and not just stitch the ditch with square blocks...lol
but what i did, i read my manual for my sewing machine, then took some large scraps and flopped them together with a bit of batting in between and started trying it out. I realize your afraid of ruining all the hard work you put into the quilts already. and you will get frustrated with free motion at first. but it is practice at finding your speed with the machine verses guiding your fabric. and of course, when you are finished, you can either rip it all out or just throw it away cuz its just scrap.
I actually went to an auction and picked up a box of fabric and pillowcases that some i liked, some not so much...and prcaticed on the not so much! Good luck and you can do it for sure!!!