Tired of waiting for quest related items? There's a maximum to the number of items you can get in a certain time frame. You will receive a message saying something like "You have received the maximum number of Mystery Gifts", after which you have to wait until being able to get more gifts. To last longer, stop sending Mystery gifts to all your neighbors, as they send back one when receiving one. Especially when you have a lot of neighbors.
Visitors spend money in businesses that cross their path, especially after they finished a ride in an attraction. Don't place businesses at the edge of your park, visitors will not go there. Use your park edge for coasters and other attractions.
Place shops between rides and restaurants. When you boost rides visitors become sick. Vomiting will empty their stomach and they will become hungry, wandering through the whole park in search of something to eat. On their way back to the rides they are likely to buy something in the shops they pass by.
The strip of land outside your park in the south west corner is perfect for placing Operations buildings like hotels and the Prop Shop. That way visitors will stay inside the park and not wander off outside. Placing them inside the park only consumes up valuable space needed for attractions.
When placing buildings on the strip outside your park, take in mind that your Goods Trucks will be there. If you want your neighbors to help you with them, don't place large buildings in front of them, otherwise your neighbors won't be able to click on them.
Move X items: move one item left and right until the desired times.
Place X decorations: Store X decorations in your Inventory, the place them back again.
Craft X items: Reload the game until you only have to craft 1 item to solve the quest.
Collect income from a business: Move the business to near your Park Entrance as all visitors pass by there and you can collect sooner. Or move the business near to an attraction and boost it regularly.
Collect income from a restaurant: Move the restaurant near an attraction and boost the attraction until it belches smoke. Visitors will throw up after riding it, become hungry and go for a meal in the next restaurant.
If you need postcards, you can activate a Landmark, then reload the game to immediately be able to activate the landmark again. You won't have to spend energy to finish the landmark's goal. Yoou will not get the landmark bonus, but you will have received the postcard upon activation.
Activating the Tower of Tomorrow will give you an opportunity to receive 50+ Inspiration. Do not boost or search buildings yourself and don't let your friends help you or start a parade, instead receive the Tour Bus. Tour visitors will search businesses for you, giving you one inspiration every time. 50 tour visitors will effectively give you 50 insiration. (doesn't work as of June 2, 2013)