patchlayout defines the size and the position of your surfaces describing the model you do. its about to decide where natural boundaries are and where trimmed boundaries are. its about to decide where you detach the skin of your models. often you dont coat your model just with ONE skin. you use different furs for covering the model and you need to decide where you stich these "skins" together.
i give you two advice:
1. go out and watch your car. Now you take small balck tape and you tape the borders of all the surface pieces onto your car. its not perfect because your car in already blended an filleted, but anyway, its good lesson. tape the boundaries of fillets, belnd major surfaces (slabs, transitional surfaces and decide what comes first.
2. imagine you have a gib block of odinary foam! take a long stiff knife and start to cut out the form you ant to have for your design. you probablly to fist the centerline cut. then you cut the width of your model. follow these steps brutally to the end and do the same in software, just without a knife. this is a good lesson as well to find out how big your siurfaces have to be and where they will be positioned. and it gives you a nice imagination which surfaces comes first.
professional modelers learned this over many years. it sa high end skill, some people say its an art. you need long practise for this.
if you use a polygonmodeler it will easier for you. mudbox, freeform and those things doesnt follow patchlayout rules.
neverthe less, if you want to do GOOD design, you MUST learn these rules. They are not just for software/digital design. you would even have to learn this when you would design for bertone 30 years back, or for bauhaus 78 years back. its basic rule about shaping things that are more or less regular. to find the patch layout for porsche 911 is a cool thing and i wish some guys in here who worked for porsch would show some of their skills. Flo???
attached is an image. you see that in the row ontop you cannot see the patchpaln and how this shapes are done. just the second row gives you an idea.
more to say but this is not the place to teach patchlayout.
as i said, its a profession.
elenor