1.
Don't spend your cash on anything you can buy with gold. 32x32 expansion and level 5 house are cash only. (courtesy Wolfie)
2. Only grow as much cabbage/wheat/pumpkin as you need for your animals and factories.
3. Rest of your crops should be tomatoes until you've progressed enough to get corn.
4. Don't waste money on trees. They give poo profit even if you make factories for them. Just buy 1 of each so you can finish the corresponding quests.
5. For Happiness, buy the three Special Items (600g a piece. Just don't bother ever using them). After those, Trashcans/Ivy Mailbox are the most cost and space efficient Happiness items you'll get for a while. Welcome Balloons are also free and give a lot of Happiness.
6. Occasionally check Rich's town and clear it out of robbers/rats. You'll get a minor exp bonus. Also, each day there are gold bonuses scattered throughout town.
7. Stop production (IE- quit feeding, planting, throwing stuff in factories) if you're going to be AFK for a while or go to sleep. Plant your entire field with Sunflowers. This is so you won't waste money by allowing your crops to wither.
8. For the Daily Bonus- DO NOT TAKE IT until 10 days have passed. This is so you can get 25 cash. Cash bonus > Gold bonus. To give you some clue of how valuable it is, 45k and 10 friends are needed for the same land expansion as 150 cash. 150 cash is way easier to get as long as you don't spend any cash.
Useful link with Gold earning rates
How to get Welcome Balloons:
One day after you started playing the game, you'll receive an email from Gaia Online about Summer Springs. Open the email and there will be a link about the Welcome Balloons.
If you do not see the email, check your junk mail folder. If you still don't get it after two days, you should send a message to the Summer Springs account (you can find them under the News Tab). They should be able to tell you if the letter was sent or not.
Welcome Balloons are very nifty because it's very Happiness/space efficient. (1400 for a 2x2 space). Also, they're free.