Easy money
Go for a long period of time just planting one of each crop. If you do not have enough money to begin with, try selling the children. You only get $10 per child, and only if they have full health. Thus, this is best done near the start of the game.
If you have a single adult running the farm, try marrying then making the spouse leave the farm. You will get $20 for the healthy spouse to leave the farm, but the amount you get when they join the family varies. This can only be done once per turn, and there will not always be a suitable spouse.
Only buy peanuts. Although peanuts are labeled as a high risk crop, they are actually not riskier than any other crop, and they are the most profitable. You should never buy any other crop unless you only have $6 remaining and all you can afford is an extra corn or wheat. Go for the peanuts immediately and continue with them onward. Also do not sell your children, as they will earn money every round. When they grow up, they can earn even more money. Instead, try sending one of your adults away in the first few rounds(especially if they get sick). Then, marry the remaining adult in the next round (make them the "head of household" to ensure the spouse comes to your farm; otherwise you may accidentally marry your only remaining adult off the farm). A new bride or groom coming to the farm will bring up to $200. Also, make sure you do not end any round with extra cash. Spend all your money to keep your family healthy, have profitable crops and livestock, and have schooling for the kids (which is an investment in their future productivity rate). Spending money is a lot safer than keeping it, because of raiders.
Save up for the Representative and the Crop Protection first; having those will lessen a lot of things that can happen to you, and the crop protection will make sure you always get a profit from what you plant.
Keeping your family healthy
Your family members will eventually get sick due to overworking or the environment. Save money to treat the entire family at once. It is cheaper to do this than to treat each person individually. To do so, click a family member, then select "Give Medicine" to get the treatment options.
Easy money...