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Fallout 4 Survival mode is not like the other modes it's not just raising the difficulty the way I see it it is a whole new game.
I am going to give you the list of things you really have to worry about.
Survival mode in Fallout 4 adds a lot of new challenges which will be talking about and how to deal with them.
The first thing you have to worry about is food and water without them you won't last a day food can be easily acquired by just planting food in your settlements or by killing animals around the map cocking the food is not necessary but it's recommended as for water you can make water pumps in your settlement and you have to collect empty bottles and fill them with water at any water resources, for example, Nuka cola bottle and Beer bottle etc.
The second thing you have to worry about is finding a place to sleep because in survival mode sleep is required if you don't sleep you will lose agility more and more by time also the type of bed matters you can't get well-rested in a sleeping bug but you can save your game so sleeping very necessary. if you're in the middle of a fight and can't sleep you can drink Nuka Cola it will give you caffeine which will delay your need of sleep. Claiming settlements around the map is recommended.
The third change you really need to worry is about the inability to fast travel at the start of the game it is going to be a problem but later on if you join the Brotherhood of Steel they can give you free rides on their vertibirds or join the institute and fast travel to them then to the location you need.
The fourth thing you have to worry about is catching diseases which come in a variety; Insomnia, Lethargy, Fatigue, Parasites, Weakness and Infection all of these can be cured either with a specific herbal for each one, antibiotic which cures them all or by just visiting a doctor.
Last but not least choosing your build I would highly recommend playing as a solo sniper with the starting stats of 2STR 5PER 3END 2CHR 5INT 6AGT 5LCK and the perks you want to focus on are Rifleman, Sneak, Ninja, Mr Sandman, Action boy/girl and Lone Wanderer. Weapons are up to you to choose all rifles should do fine but if you can afford overseers, guardian, I would recommend that but whatever rifle you choose it has to contain a silencer to make use of Mr Sandman perk.
Of course, perks like Armorer and Gun Nut can be useful if you invest in them just the amount you need or science perk if you are planning on using a laser rifle. Deep-pocketed mod for all your armours is necessary because the carrying
Companions will only blow your cover and power armour can be useful if you use Hot Rodder painting to enhance your agility.
Chems can help you from time to time but addiction is very bad that is way accessing a doctor at the start of the game is very important (I think the closest Doctor to the start of the game is at bunker hill)
Good luck out there and don't do chems.