Hi. Hope you don't mind some constructive criticism.
You've put quite a number of objects on the road - specifically the start lights and arrow markers.
Things that can cause injuries in real life shouldn't be on a track. I'd put the lights behind the armco barrier, or something else, if available.
The marker boards, which in real life are usually made from polystyrene usually wouldn't matter too much, but there's enough 'street furniture' round a track that you can put signs up on lamp posts, street signs, traffic lights, fences, buildings, etc, to keep them out of the way - and usually in better places to see them. You can even make your own poles if needed.
There's a section, just after the start, where there are overhead direction markers that are pointing in wrong direction to where you want drivers to go, so these should be covered to stop any confusion.
Can't say I'm a fan of the very sharp corners you've used, nor the barriers with hard edges just sticking out into the track, as per the barriers for your chicane. Better to round corners into arcs and/or put tyres on outside of barriers.
Finish line. I much prefer when there's an actual finish line of some sort that you can actually see. The line you place to tell LFS where finish is, is invisible, so I tend to use straight coloured chalk lines on ground and/or an overhead banner, which is simple to make with just a pole either side of the road, with a cement wall joining them together.
Tip: If you want to make objects intersect to give better placement, lift and drop objects, and LFS will allow them to 'join'. I use this a lot when I want to make an arc of tyres that look like a solid wall.
I've amended one of your layouts to show what I mean with the points I've raised - see attached.
As far as making layouts, I've only ever done it by hand/eye using the LFS in-game editor, so the more you use it, the easier it gets - evem when using maximum amount of objects.
Feel free to ignore this post if you want