Yes, you can marry the harvest goddess and have 2 kids in fact! But she won't live with you on the farm because of her 'duties' as the harvest goddess. She will only come visit when she has your kids, on your birthday, and on your marriage anniversary! Once the kids grow up, you can ask them to do your chores since the mom can't. Now, in my opinion, i think farming is the best way to get lots of money. Read down for more info.
To earn a lot of money in animal parade, you'll need to ship a lot of items that sell for a lot once you ship it in your shipping bin. At the end of the day, you'll recieve your pay in each of the following categories: farming, ranching, mining, fishing, and others.
RANCHING:
To earn money in ranching, you'll need a big barn and coop which can store a lot of animals in them. If you have enough money to buy both the upgrades and the animals, i suggest that you upgrade both your barn and coop to the max. level, which is lvl.3. A lvl 3 barn can store 8 livestocks, and the lvl 3 coop can store 8 chickens and 4 silkworms. For your barn, a cow and a goat can be an easy way to earn a lot of money since they give you milk everyday. Buy a cheese maker, but not the butter maker since cheese are more expensive than butter. Duck eggs cost more than chicken eggs, but ducks lay an egg every other day, so it's best to have an equal amount of chickens and ducks so you can recieve eggs every day. But ducks are more suggested since even though at the beginning they will lay you decent eggs, if you buy a mayonnaise maker, then there is no rank to the duckonnaise, so a decent duck egg can sell for the same as a good duck egg. (You can only buy the mayonnaise maker once you upgrade your coop to lvl 2 , i think)
FARMING
Farming is a easy way to make G since each season, you can buy various seeds to plant and harvest.
spring: The best crops to grow is strawberries, but the seeds cost a lot, and the time of their growth depends on the quality of the soil they are in. (So you'll need some money to start with on the seeds and fertilizer). But the good thing about strawberries is that they can reproduce. I would suggest that you fill out around a quarter of your plot(s) with strawberries and the rest with plants that can't reproduce. (Choose lettuce)
summer: Summer is a easier season to earn money in since at the beginning of the game, you get some cherry trees (The trees on the side of your home plot). Cherries can be harvested during summer, and to harvest them, you have to push the trees a little to make the fruits fall. One tree produces 2 fruits a day. Also, during summer there is a lot of expensive-selling crops to plant. I would suggest the tea leaves since they can be harvested in 3 days and they sell for a lot. But if you think that the price of the seeds are too high, then just plant a little bit of your plot with tea leaves and the rest with, sugar canes, watermelons, or cucumbers. Sugar canes can be grinded at the Horn Ranch big windmill, but you can only enter once you rang the green bell. Once you grind the sugar canes into sugar, they can sell for more. Try going there during windy day and sunny days, and that'll give you a boost in the quality of the sugar. (decent sugar cane + windy & sunny day = good sugar)
Fall: Fall is the season where you can earn the most because of the expensive flowers you can plant called, the blue mist flower. These flowers can sell for A LOT. If you plant these flowers throughout the season, you'll be sure to earn like 200 000G.
Winter: Winter is a bit harder, but try to plant all the seeds. (buckwheat, snowflake flower, anemone) For the flowers, you can wait until bees come to make honey. Honey can sell for more.
FISHING and MINING:
Fishing and mining are probably the hardest way to earn lots of money since some fish can sell for as less as 7G! The only fishes worthwhile to catch are probably the King Fishes, but they are extrememly hard to find and catch. Mining is hard as well since you'll need a lot of stamina once you go into the mines since you'll need to break the rocks to find ores and wonderfuls. There are also lots of gases in the mines, which are really annoying to deal with. (poison gas - loses stamina...and more!) Also, you need to refine the ores and wonderfuls into jewels and metal to actually earn the deserved money, but this requires luck. If you have played Tree of Tranquility, to refine ores and wonderfuls, you just need to bring Mira the rocks with the sparkles on them. But not in Animal Parade! There are no ores and wonderfuls with the sparkles, just plain ores and wonderfuls, so you'll never know if they can be refined into jewels or junk. The stuff you refine is probably around 80% junk and 20% jewels.