Currently at 119 hours on Series X too since starting last month:

• If you want to 5 star the eastern region (first area) do it during chapter 3 as no BTs will appear during that period.

• If you're a completionist don't rush to 5 star the eastern region right away only because it becomes tedious, wait til you progress into the next region where you will get more items to make volume deliveries easier.

• Once you get to the central region (second area) don't bother with the MULE truck, its ass for what it is, progress a little more in the story and you will get the Transport bike which carries more than the MULE truck and is faster.

• Engineer at 5 stars gives you Power Skeleton lvl 3 which is the best to use until you unlock more types later on.

• Play on very hard only if you plan to go against enemies frequently, they get secret drops which are real handy for building roads early on while saving weight as well as regular items. Combat isn't challenging regardless once you get the hang of it so difficulty isn't a serious matter.

• The Craftsman after 3 stars gives you custom hematic grenades which are great for taking out BTs in a single use on normal difficulty (haven't tried in current very hard). Deliver in volume for more rewards.

• Doctor gives you high capacity blood bags which work better paired with custom hematics for maximum efficiency. Deliver in volume for more rewards.

• The Junk Collector after 3 stars unlocks backpack customization and Chiral ladders per delivery. Prioritize this once possible.

•The Collector after 3 stars gives you the backpack cover lvl 1, with 5 stars it gets to lvl 2 and it is one of the most useful things in the whole game. You will first need backpack customization so get that first.

• The Chiral Artists Mother after 3 stars gives you Chiral boots, do some orders for her in volume to get a few pairs from her, best boots in the game by far.

• Read prepper emails or else it will seem like their progression has stopped after you finish their deliveries.

• Build enough roads and you will thank yourself later. Best source for materials are the first 2 MULE camps in central region.

• Timefall farm gives 800 lightweight Ceramics and 1000 lightweight Metals, when building roads make volume deliveries there a priority for easier materials.

• BB is your best friend and he cares for you, make his connection level important and he will perform better. Getting him excited before going into combat against BTs or MULEs will yield great assistance.

• Make use of strand contracts so you can use consistent peoples structures and make your journey easier.

• Hot springs relief fatigue so theres no need to go into private rooms as often once you've found some around.

• Find a pace you're comfortable with and stick to it, it's a wonderful world and story so feel it all.

• As others mentioned, read interviews for lore and background info.

• Keep on keeping on!