When you are making terrain or scenery, it is always a good idea to keep a figure or two of the scale in which you are working nearby. This allows you to check often to ensure that buildings, vehicles, and blockades will look proper and that figures can actually fit where you want them. This also ensures that figures can see over hills or hedges and that doorways and windows look like they could actually be used.
In addition to having the figures handy when at home, it is also a good idea to carry a figure around with you when you are out and about. When I first started into 40K, I carried an unpainted plastic beakie marine around with me for about a year. After that I had a good idea of the size needed. Plus I found that, in a pinch, if I bend my pinkie, the middle joint is close to the size of a marine (being a bit over an inch long).
With starting to make scenery for my western figures, in roughly 1/32 to 1/35 scale, I should really start carrying around a cowboy in my pocket. This would really help in trying to find horses and cattle – both of which can come in random scales and can often look tiny. This will also come in handy in finding wood I can use for scale log cabins.
I was in Dollarama recently and noticed a nice folding bamboo fence that might be a great size. I didn't pick it up yet but may pop back with a little buddy. Otherwise, I was thinking about looking at those disposable chopsticks to see if they are cheap in bulk.