I use a lot of signs and construction fences to make tracks with multiple routes.
Signs would help a lot in directing the player if they didn't appear so negligible. Unless they're placed in such a blatant way, which usually uses more prop space, most players just don't notice them. All they need is a small aesthetic change so you can differentiate them from generic road signs.
I usually place construction barriers where I can. Either inbetween cp's or alongside them if the course changes. Or if things are absolutely impossible to place, then I
will make it a GTA and place boosts along the path to help.
This is actually a major source of contenton for me.
Rockstar should make ALL terrain available to put barriers etc on. It's a real bitch trying to make off road tracks and I could do with another 50 available constructions too.
Good point, even if a flat road has too much gradient, it won't let you place props alongside it. his is something I hope Rockstar refine in future, possibly more options will arrive in the Capture update.
I hadn't thought about the use of GTA Race pickups as a way to guide players but it's a good idea. I'd imagine it would even it encourage players to deviate between different routes if they're made to choose between say a boost on one or a rocket on the other.
Opinions have been mixed; a few people complained it was disorientating; one rage quit due to respawning so far back after crashing, and nobody really seemed to know the quickest routes and short cuts. I think the idea has legs, but needs refining.
It is a major part in the balancing act, not having checkpoints so far apart that players spawn too far back. but of course the nature of having multiple routes means you need spaced out checkpoints. Having dual - quad checkpoints, or have the player spawn near where they crashed instead of at the previous checkpoint would fix this.