1. Always big production room
Yes, there's penalty, but ♥♥♥♥ that. Place different kind of deco, plus an "award", that can give you a x2 on decor bonus. R&D can reduce the machine decor penalty. You can have 400+ bonus to be deducted
Big room ensure the space use far more efficient. Doors and wall is waste of space and making labour path longer and slower.

2. Evenly take the order of Steel, wood and plastic
Dont rely on single kind of product, so all your machine can earn you money.

3. Understand your material flow
Loading bay --> general storage --> specified raw material shelve --> raw material processing machine --> semi finished product put to general storage --> specified shelve for assembling --> finished/ semi-assembled parts at general storage
Always bear in mind you should have both general storage and specific storage near all your workstations. Its the only way to let the hauler to do the logistic.

4. Assembling workstation group in 4-6, dont make the group too large
The assembling workstation can complex up to 5 stage. Simply put all assembling tasks into a single workstation group can really stuck the whole process.

5. Never duplicate deco and break room items
Yes, the game didn't tell you. But you'll realize every duplicated item has a 50% off in it's ability. Split it into different rooms. Never mind, break room can be as small as it can. Save some large room penalty.

6. Monitor production progress. if stuck, solve it.
Yes, there are bugs in game.  Labour can stand and do nothing, even raw material arrived and forge machine ready.  Save and load to previous game stage can help.
If you realize the estimated finish time is over 10days. There's a need of increase machine or manually split off the tasks to different workstation. Billbroad is simply not a perfect solution.

7. R&D advice
High Priority: any beginning techs
Mid Priority: advance machine (you need to be rich)
Low Priority:super machine (insane pricing)
Not recommend: market refresh

8. Dont do over quality product
Product design is the core of the game. Use your idle machine. Pick the cheapest material first (it can costs you double of different material)
Always stick to the requirement. Otherwise, no profitability means game over.