I would focus on design the thing as much as partitioned as possible so you have the minimal amount of shared things across threads. If you make sure you don’t have statics and other resources shared among threads (other than those that you would be sharing if you designed this with processes instead of threads) you would be fine.
Therefore, while yes, you have to have in mind concepts like locks, semaphores, etc, the best way to tackle this is to try to avoid them.