My layout is entirely blue insulation foam board and I have come up with a good number of tricks for working with it.
With my track - traditional tubular 027 - I laid out all the track first, then tested a loco and a few cars. Then I made a diagram of where I anticipated track blocks would be, and put in insulating pins in the center rail. Once I was happy, I made wood slugs that would fit tightly beneath the metal 027 tie. I cut a piece of 3M Carpet Tape on one side of a wood slug that I cut, put the wood slug loosely into the metal tie, and then pressed in on to the layout surface. The wood slug with carpet tape held everything in place well enough to continue working.
I then drilled some small pilot holes into the wood slugs and then used Gargraves #4x3/4 screws to attach the track. I found I didn't need to attach every single section of track. But because I have heavy modifications to my switches (the metal backing plate is removed and the plastic base of the switch is cut down to literally just the track) I found I need to attach slugs and screw down the track closest to the switches.
I later added individually cut wood ties to the track and then used Woodland Scenics HO ballast adhered with watered down Elmers Wood Glue (so that it did not come loose with repeated applications of the watered down glue). I could then remove some of the screws as the glued ballast helps to hold the track down.
Most buildings are designed to come loose from the layout and are in place with foam core board pieces I cut to the size of the building, which then fits snuggly over the cut base. Trees are held in place with drinking straws that I rough sanded, then wood glued into a hole in the foam. This allows me to remove trees easily, or even switch them around. If I decide a tree was placed someplace where I don't want it, I use Expanding Insulation Foam to fill the hole. the Expanding Foiam is also a handy scenery building material.
I have my own custom designed icing station which I had orginally made as a prototype for K-Line. The building has been though several changes, but still works. Instead of gluing it in place, I made a wood "track" and modified the structure tower so the the whole thing slides nicely into the wood "track" I made.
My mountains and "tunnels" take their inspiration from all those Road Runner cartoons where the Coyote was always falling off a mountain that suddenly just ended. So the mountains are build up out of foam board and then jut out over the track, sort of as an upside down "L" shape. Once the build up foam mountains where dry (glued together with wood glue) I could use a utility knife and screw driver to make nice convincing rock formations. When I need a hole for wiring in the mountains, as one has a light tower on in and the other a Bachmann Log Cabin with a smoke unit in the chimney. I heated up a piece of brass tubing over the stove, and then pushed that into the layers of glued foam board and got a very nice hole for wires.
Accessories like light towers either have a special base made out of black styrene (which I got a mountain of for free) which I use the carpet tape to adhere the styrene base, then I can crew the light into that. Others, like the K-Line light tower or bubbling light tower are inserted into the foam base. I cut a hole into the foam the size of the base. I pushed out that piece of foam, and then cut the foam thinner to allow the light tower to be flush with the layout surface. I then used wood glue and masking tape to re-insert the thinner piece of foam into the layout surface.
I took my MTH Operating Platform and modfied it as I wanted it much smaller. So I cut off a inch or more off both sides, including the base and roof. Then I refinished it, touching up all the changes and again made a holder out of wood that the platform fits snuggly over. This way, I can remove it very easily.
My scenery material is mostly spray painted saw dust, with also cooking materials like thyme, tea leaves and fish pepper, and black, brown and normal colored sand, and also ground up tree leaves and coffee grounds. I use the same watered down wood glue to attach all this.
My layout is rather small yet very impressive for all the action, scenery and accessories. And it's lightweight and moveable if need be.
And I also put a couple of switches on the curves on the ends of the layout for the very real potential of one day expanding the size of the layout with another modular section.