If you are low on money, make sure you have several dice(best 5 or more) you will get next turn. Or if you use all your dice, make sure you have some income.
It's frequently hard to start up again if you have little money.
It is better to save money then build a costly building than build a costly building then try to recover more dice.
There are two ways to get income:
1. select explore and then choose to stock (usually $2)
2. If you have goods on your worlds: select ship and then trade (usually 4-6 depending on colour).
Method 2 is a more productive way if you have green or yellow worlds, method one is more productive if you only have a blue or brown world (though there are many ways to measure it...)
How many turns it takes to get income (produce + ship = 2, explore = 1), How much money is profit per die (explore costs 1 die and produces 2 = 1 profit, produce+ship costs 2 die produces 4-6 = 1 or 2 profit per die)
Other factors may come in to play - 'acting like there is an extra die' in a phase helps bolster the income, being able to do the action more than just once (e.g. three produce and ship can yield credits $6 and 6VPs which can be sustainable every two turns)
Selecting dice to Scout/Stock 'currently' has a bug -- For example, for Alien Archaeology ALWAYS use your yellow die first, regardless of which die you select to explore with. (not sure when author meant - pre 04 May 2020)