When the game starts, buy 50 cups, 50 sugar, 1 tree, and 10 ice swings... keep prices at .25 and make the recipe 7 Lemon, 5 sugar, and 10 ice. When you can afford the newspaper ad (and maintain your supplies), buy it and raise prices to .35. When you can afford the radio ad (and maintain your supplies), buy it and raise prices to .50 (try to keep both ads going at the same time... should be rather easy... don't let the radio ad lapse). When you can afford the TV ad (and maintain your supplies), buy it and raise prices to .85 (try to keep all ads going at the same time... should be very easy). Keep everything steady until you reach 100% for customer awareness/recommendation (I hit it at day 22). After that, name your price. I pushed mine to 2.50, then 3.50, then 5. On the final day I raised it to 10 and they were still buying (although very few). Ended up with $2,084.90.
The two extra trees are not important until late in the game and by that time you'll have lots of extra cash (hundreds of dollars). When you're running low on lemons, buy the other two trees at the same time, restock your supply, and start using the "water all trees" option from then on.
Also suggest purchasing 30 ice swings soon after you get the TV ad (you should have lots of extra cash to spend).
I finished with $4074.55 believe it or not. Here is the strategy:
buy one lemon tree and a 10 pack of ice and 50 cups of sugar and cups
make recipe 2 lemons 3 sugar and 10 ice
raise price to fifty cents and go up 25 cents every 3 levels
save up for all three advertisments at one time and buy them
Eventually buy all the lemon trees and always have more than enough supplies and advertisments