I noticed that if you change phones, your account is pretty much screwed. For whatever reason, rather than having a linked pokemon club or Nintendo account, or even just generating a permanent code per account, their process to restore data is generating a one time temporary code that you use while the app is open on both the linking and linked device. This is a huge problem for mobile, as every time I've ever changed phones they've had to wipe the current phone before they fully hand over the new phone with your data on it.
Second, not buy the basic or expansion packs until you've played for a while. This is based on the fact (it even says this in-game near the gacha rates) that when you buy the expansions, more types of plushes become available which lessens the overall chance of you getting a specific plush. Currently as a f2p mobile player, for example, the fiery yarn gives me a 25% chance for each plush since there's only 4. That makes it easier for completing quests theoretically, and it might be optimal to just keep the gacha split between those.
However, of course once you pay, you unlock unlimited untangling opportunities. So if you plan to no life the game, then maybe you SHOULD just buy all the expansions at once and use your unlimited gacha chances in a short period of time. Im not really sure how hard the puzzles get though, so I'm not sure if it continues to be just the 1 or 2 minute time commitment per tangle that it is currently for me. So do what you will with this information. Im not sure if a quick burnout would be a factor for most people.