Factories are kind of tricky. Here are some hints that might help.
Basically you should have enough raw material for the factory to work with. Two sources of raw material per factory is generall a good guideline. The exception is the lumber mill, it can manage on one logging camp with the improvments implemented.
Don't expect to make any profit the first few years you build a factory. Plus you will take a hit in your exports because the raw material will no longer be exported. It takes a while before the factories start producing.
Implement any improvments you can to the factory. They will speed up production.
If you have an airport and foreign ministry, you should try to send trade delegations frequently to up the prices of your finished goods.
The industrial advertisement edict which you can use once you have a television station raises your export prices for a short while. This also helps.
Lastly, make sure that your factory workers live close to the factory. The factory will produce as much as one worker's output when there are no workers in it, but the more the workers, the better the production.
Hope that helps.