One common cause for comment among SSHM players is a desire to reduce the number of quests on their desktop (in fact, my desire to reduce the number of quests from the 27 I had led me here to this wiki; I am now sitting at 11 quests and do not expect to get much higher than that going forward).
Also, the order in which the game issues pages for your player's diary is dictated by gathering certain collections, opening pictures, or completing certain challenge quests.
If you are one of those players wishing to reduce the number of quests on your desktop, you have come to the right place. However, there are just as many high-level players that actually say the game becomes different once all the available quests are completed, so choose your path.
The first thing you need to do is to make a list of the items being sought, then do a search for each within the "Collections" tab to determine which collections they belong to.
In some cases, you may instead have a 'general' quest in which you are merely asked to investigate a certain picture or play a certain puzzle - it is suggested that these be taken care of first.
There are a few "one-off" quests that also appear, mainly within the lower levels, and these can be a bit of a challenge to complete (one one-off quest is also easily confused with a collection quest as well). These can be confusing to a newer player, as the items often do not remain in inventory after the quest is completed. Where possible, one-off quests will be indicated when they are known to appear in a given series.
Once you have determined which collections the items you seek belong to, look for them in the lists below to find which "series" they belong to, and which should help you prioritize the order in which they are to be worked on, whether one is near the end of a series, or a series that is much earlier than the others.
Because of the large number of quests, this 'handbook' is separated into three parts:
Book 1 - Quests for Levels 1 to 49:
The majority of the game's one-off quests are within this section and it is easy to get lost in terms of quests at this point.
Book 2 - Quests for Level 50 and beyond:
After a confusing beginning, the game settles into starting a string of quests every few levels.
Book 3 - Challenge quests:
These are quests that were introduced during the various game events over the years.
Depending on when the game was begun, some players will not have these among their quests.
(Players starting after March 2018 will not see these quests at all, as they are 'expired' from the games, BUT NOT the items).