Are you moving your characters straight out of one task and straight into another? This is what I was doing when I began playing the game. Sometimes it takes a few seconds after a character finishes a task for the exclamation bubble to come up (and this seems to happen more often at higher levels). This means that it can be very easy to place a character in a new task before you have the chance to realize that this is just the character you need to move things ahead.

I’ve found it helpful to collect on all the “thumbs up” first, then the rent, then to look for anyone that has an exclamation mark. This stops me from rushing a key character into a new task, particularly when that’s the character that starts the next quest.

It’s also important to complete all the tasks in your task bar, particularly at early levels. The tasks happen in a particular order, and missing one out can halt your progression (the only real exception to this at lower levels is the friends’ task).

Also, always pay attention to how many times a character needs to do a particular task. It’s usually only once, but there are a few tasks that need to be carried out 2 or 3 times for the task to complete. You can check this by tapping on the task in the task bar. If it says 1/2, you’ll need to do it again before you can collect our reward and move your game along.

Finally, try to have all your characters finish their tasks at around the same time (avoiding mixes of longer and shorter tasks wherever possible), so that it’s easier to see which character generates the next quest. This is particularly helpful for quests that involve a number of characters.

P.S. – an event like Valentine’s Day can slow the normal progression of the game. The Valentine’s Day quest involves Homer, Lisa and Mlhouse (as well as Marge), who are all important for early game progress.