It is highly advisable to follow the exact order of this Walkthrough, the in-game advantages that you unlock periodically are significant and can cut many hours and frustration from your time played.
It is also advisable to do the Main Campaign and Activities simultaneously at your discretion, and it is essential that they, especially the Activities, are done in Co-op first. These are the most advantageous aspects of the game to complete before all else. Complete part of the Main Campaign in Co-op first, then do the first recommended Activities in Co-op, then return and continue with the Main Campaign again until all are completed. In this way you will unlock friendly neighbourhoods and various advantages making the gameplay much easier and enjoyable.
Save regularly! This game is very prone to screen-freezing, and many, many mission breaking glitches. Both you and your co-op buddy should save after every single main mission, after every 6th level of an activity, and after every single collectible. It only takes about 10 seconds to save your game and it can in turn save you hours of replays.
I would also personally advise boosting the whole of the multiplayer as the legit multiplayer is extremely annoying.
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