In case you wanted to know about the bug hunting, if you catch
only high-worth beetles on the island, they'll have to be beetles that spawn on palm trees. Also, a full island-storage full of beetles are worth about 300-350k per run without the bell ordinance, and about 400-450k with the ordinance. It is very time consuming.
If you go the easiest route of Time Traveling, you'll have to be sure that you don't care about the town's looks or villagers moving in or out. You can (recommended to) go with the beautiful town ordinance to make sure you don't wreck your town by making it polluted by time traveling. You can make 99k
per character from interest by time traveling. You should have at least 100k when doing this, (if not, it'll just take a bit longer), time travel
12 years ahead and you'll get 99k. Give this to another character that you control and store the money in the ATM. Then travel 12 years again. Keep doing this until you have all 4 characters with at least 100k in their bank, and you can just keep traveling back and forth. This way you rack up 400k per 12 years. (As you get more money, the less years you'll need to travel)
If you decide to time travel, you'll need to know that 99k is the maximum interest you can receive at one time. That means, you'll have to log into your character every time you time travel (only your main character, you don't have to go on all 4 of them) in order to "reset" the interest capacity. In other words you can't fast forward 24 years to get 198k, you'll have to do it 12 years at a time.
Here are some better guides for the previous said methods--
Beetles:
http://kotaku.com/the-best-way-to-catch-beetles-in-animal-crossing-new-l-786858471
Time Travel:
http://www.gamefaqs.com/boards/997811-animal-crossing-new-leaf/69312808