As for houses since my style is all over the board, check in every 4, play every hour cuz I can, play every 12 cuz I'm busy and there's the "need a break I'll check it tomorrow"
I also don't like the look of house farms in my town- so as with everyone else, I play my way. Using that info, here is what I did-the important thing is every suggestion you get will be applied or not, depending on what works for you. This is only how I did it and why's.
I recently went from level 177 to 939 in about 7 weeks, and that was a full out grind.
First, what is your multiplier? Getting that number up makes a crazy amount of difference. If you're making 1-3 donuts a harvest (KEM) you could go to the mystery box route of one a day or so. Me, I saved and bought small items with multipliers from the store as I went along. Slower, but I don't have a ton of itchy scratchy bill boards or news vans to hide. Took me over a year to get my % up, now it's getting easier so it's moving up faster.
If you have the XP collider RUN IT. Regardless of anything else the 5x on both xp and $ is well worth the precious donuts. That was one thing I wasn't doing over that year or so and I robbed myself of a lot of donuts that way.
Don't forget the monorail and where's Maggie, both no brainers for free donuts. Even if you only store the rails, you still get 5 donuts every week and up to 3 every 48 hours with Maggie.
Don't forget the dailies too, every 10 or 15 plays (depending on the random set) you can get another pile of donuts. I had one once, play 15 times for 20 donuts.
Another purchase to save/spend donuts on really is those hideaway beach places. They are difficult to layout if your about designing but once upgraded (first building is donuts and upgrades are SH currancy that your characters generate) equal 100% to your multiplier. It's a pain but with it. Each upgrade and original buy has one item in it that has the multiplier, it's the only one you need to have in the water to get the %. IMO it seems the less attractive of fun pieces have the % which figures. :)
@Muhsterino has the thread for beginners (stickied on the top of our threads) that has a world of info in it.
If you are playing freemium, patience and persistence are your best strategies. If you can afford or are willing to put in real $ then select your purchases for what you like first and what gives you the best set up. I went back and forth from decorations with best % to buildings I liked with payouts. In my book every little bit helps but I have to like my town first.
Course as "they" say, whoever the hell they are, What works for me might break you and that goes for all of us.
Take what you like and toss the rest :) :)
HAVE FUN!!!