1) Spending – Fiscal Policy: the government borrows money, then spends it on any number of projects. This puts money in the hands of consumers, consumers spend on things not related to the projects, and businesses respond in order to serve demand. Their employees spend too, and the cycle expands. Problem? It takes a long time for money to move into the economy.
2) Monetary Policy: the government borrows money and then auctions it off at low rates. Bankers buy this ‘cheap’ money and sell it as lower cost loans to business and the public. Problem? Sometimes (now) no matter how low you make the cost of credit (effectively zero) people will not borrow it.
3) Trade Policy. Sometimes you can tax or reduce taxes on goods and services to make them cheaper or more expensive. So, for example, if you want to create jobs in say, clothing manufacture, you highly tax clothing imports. Problem: this just makes goods and services more expensive for consumers, so it has to be paired with monetary policy.
4) Industrial policy: what we did with the auto companies. You find a way to create or expand industries that create jobs or create demand.
5) Education policy: train or retrain your population to produce goods and services that are desired, when the goods and services they produce are no longer as desirable.
Most of the time, governments quickly adjust monetary policy then they try spending policy. The argument today is that we should spend more. The problem is that people don’t trust their government to spend it wisely, and they therefore prefer to suffer a slower economy than fund bad behavior in government.