I have never found it necessary to use two layers of WSS when preparing my hoops with thin rubber shelf liner (why unnecessarily waste expensive stabilizer?). The tutorial can be found at Criswell. Also, don't tighten the tension screw on your hoops after hooping--this causes warping of the stabilizer which can cause your design to become out of registration. Look for these instructions about 1/3 the way down the page at The Flying Needle. Read the entire article there for some great hooping advice. Finally, use the smallest hoop available that fits the design and a fresh, fine (#11 or #12), sharp needle
Luck was with me on my first FSL design it came from our generous Liane at http://www.ls-liane-stitch.de, try two layers of wss if you wss is very thin it helps to keep stability while stitching and do not forget to keep breathing - LOL it is so fascinating to see a FSL come together.
Tavernmaker has lot of freebies for FSL...they recommend the same thread top and bobbin...and if you want the look of cotton hand crochet, they recommend serger thread...I know...believe it or not. Depending upon the quality of your serger thread, you may need to clean the bobbin case...lint can build up...but it works great...if you want some beautiful freebies, they have several and their designs sew out so beautifully...
bevintex gave you great advice. The tutorial will be very helpful too. Don't be afraid, just dive in and try it. We were all newbies at one time. So don't be afraid.
emblibrary has a tutorial and there are plenty more on you tube. Be sure to hoop tight,use same color thread in your bobbin and I prefer vilene the fabric type wash away over badgemaster or the clear plastic type, for your first try(if you are new at it) make it something simple until you get the hang of it. Use the smallest hoop for your design and try putting just one design per hooping,otherwise it can shift or stretch out of place, most important if it doesn't work for you the first time don't give up.try,try again