On March 23, 2018, Zygor Guides announced that they would end support for their ESO guide. Later, via answers given on the forums, they confirmed they would not add a leveling guide for Summerset. Their guide is Public Domain with Zygor's blessing for the community to create guides. So I took it upon myself to create a Summerset guide for the ESO community.
Only really to expand on Gráinne's comment as regards the 'collecting' and 'roster development' sections - which are, as said 'distinct' although they are intrinsically linked - I would like to point you in the direction of the in-game Achievements > Battle Pets > Collect tab. There are a series of achievements called Raiding With Leashes, pretty much all of which can be completed via the auction house - if you have the gold/inclination - or by completing old raids.
For example, the Azure Whelpling belongs to the Dragonkin family. However, it has Beast, Magic, and Elemental abilities in addition to a Dragonkin attack. Different attacks are strong and weak against different family types. Having a diverse spell selection might increase your chances of being prepared with a strong attack against an opposing team.
Through out the game, the quest log will be capped to 20 many times. The guide makes use of maximizing the total amount of quests you can accept at once. Because of this it is important to follow the guide exactly and only accept quests if the guide tells you to so you won't run into issues not being able to accept a quest. If you do accept a quest that is not listed in the guide, write it down because you may need to abandon it in order to keep following the guide if your quest log is full.