Before playing Umbra Fields, have some small quick tips and tricks.
Class Related tips:
Warrior: Very well balanced. Made to do anything with a focus on physical attacks. Put your bonus points into physical attack and magical defense. Recommend for new players.
Doctor: Doctors are very strong, as they can quickly heal injuries and is immune to the Plague. More of a support, they reply on other party members more. Recommend for new players.
Thief: Is very fast and can steal money and items from enemies and shopkeepers. Most shopkeepers will not sell to Thieves, and their wanted level will always be higher than most. Focus on agility with bonus points.
Hunter: Hunters are focused on their bows and being very aggressive and offensive when possible along with having traps to cause debuffs to enemies in battle. Physical attacks should be buffed with bonus points. Recommend for new players.
Rune Master: Rune masters are all about setting up stronger attacks with runes. Some unique locations only they can discover. Requires more strategy than most other classes due to this reason.
Summoner: They can summon creatures to protect themselves if they have the materials and find a summoning circle. Mostly a support, they can create some of the most powerful minions if they travel and explore enough. Requires lots of strategy until a strong minion is created.
Ice Spearmen: Fishermen who fish whenever they can find any remaining, clean water. Fish can be sold or eaten for buffs and healing. They are very self sufficient, and spending some time fishing whenever possible is recommended.
Investigator: A detective that can use guns, talk to enemies when able, and can take on cases for others. If you are cunning enough, some will join you by speech alone. Some will also take the pause to attack instead. Requires more strategy due to all of the new options available.
Priest: The Gods need priests to spread their holy words, teaching them holy magic. Priests are made to travel the land to find a god or gods to worship, and in return strong holy magic is learned which gives a very strong buff. Recommend for new players.
Brute: A Warrior that has no honor, fierce in the wild, yet cannot live among civilization. Very aggressive in their main attacks and less defense than the Warrior. They require bonus points being put into defense, especially magic defense.
Storm Evoker: The Forbidden one was one of these, a being that can control the storms. The outcasts worship Evokers, others fear them. Mostly uses physical attacks and lighting attacks, they can be a major force to anything in their way.
Fowler: Flying beasts that can travel to any place they please, but are hunted. A Fowler can quickly travel to place to place to experience many things easily and quickly. They have the weakest defense and can easily be stunned. Defense in Magic and Physical is required with bonus points, and getting new armor and accessories for more break shields is needed.
Fire Elemental: Due to the Great War, The Flame has made all Fire Elemental to be worshiped and adored. Yet not all feel the same way. The Flame is the best nation to start at due to all of the bonuses. Talking to other fire elementals gives free healing too. Very aggressive, magic attack should be focused with bonus points. Recommend for new players.
The Slime: A mistake not meant to live. An experiment to remove all bones so you can no longer be injured and stronger in battle, it comes with a downside. Your body is made out of a liquid mush that is weak to everything. Only those who wish for pain choose the slime. The slime can quickly be killed due to it's weaknesses, so it must spend the most time to prepare before bigger battles before fighting to make sure it won't easily be killed by getting new armor and protection. This is mostly something to be a hardmode for anybody who wishes for a harder experience.
The Blameless: One who is random with their speech, and their spells. They cannot be blamed for their actions, as every time they open their mouths, it is unknown what will come out. Beasts of the Umbra Fields attack them last, knowing their randomness can be beneficial. Getting party members will drastically improve your chances of survival, and it's random main spell can be beneficial or harmful at random, so putting too much faith in it can be devastating.
Nation Related tips:
The Flame: Highly recommend playing as a fire elemental for choosing this nation as a starting nation due to the benefits. If your class isn't one, then it won't be as easy of a time.
The Land of the Sea: Islands can have some strong treasure, but are usually protected. The zombies that protect them are very easy to kill, outside the main Shamans.
The Gaea Forrest: Since it has the most infrastructure that remains, it is the easiest to travel in and explore. Very non-linear, so you can do anything in any order to gain any skills in any order. Going to the school gives free stat points, while the fortune teller's abilities are very strong.
Angelic Constabulary: The Guardian party member can be gotten here if starting in this nation, doing side quests can increase it's potential. Taking to the scientist after each main quest for the nation can give some free skills as well.
The Prison: Has some strong party members to recruit, and the prison food is strong. A doctor is immune to the prison food's illnesses.
Lich Fields: Lots to explore and find, with very strong weapons for daggers and staff hidden away. Thieves and Fowlers can get some of their strongest weapons here.
Pig Nation: The luck blast is one of the strongest attacks that can be gotten with luck. The Pig Bonds are great for storing money along with the Bank so it doesn't get stolen in battle. The Arena is a great place to get EXP and money.
No Man's Land: If the player isn't an outcast or of certain classes, then it's best not to stay too long.
General tips:
In the first area, it is highly recommended to do all of the side quests for their specific skills.
Side quests are the best place to gain more strength and skills for battle. Do them when you can.
If you do get the Chocolate Truffle and deliver it into No Man's Land, there is a major reward that can drastically help with survival.
Exploring is one of the best things you can do once you believe you have everything from the nation you are in. Beware of No Man's Land, it doesn't have a lot for those who don't live there outside hungry beasts.
Injuries and aliments are key to success. Physical attacks can cause injuries quickly, and Magic attacks can cause an aliment based on the element being used. Some enemies get stronger when injured. Most get weaker. When Injured, concussions are the ones that last the shortest in battle, but has the biggest impact. A single injury or aliment can turn the tide of battle instantly, and some attacks cause them more than others. Getting armor to resist them would be highly beneficial.
Boost Points are very strong for boosting abilities and using stronger ones locked behind them. Save them for bigger attacks or to boost abilities when closer to the max amount of them during battle.
Magic stones are very expensive but very strong in battle. Boost Points can be used with them in battle to quickly kill enemies. You should save them for minibosses and bosses you are stuck on.
If fighting against a Thief, killing them gives lots of gold, but every turn is another opportunity for them to steal. Running away from a Thief might be beneficial if you cannot kill it fast enough.
There are some hidden, secret bosses and routes. They are much harder than the stuff in the normal game. Only attempt them if you have a full party and are strong enough.
I recommend playing on normal first, since the other difficulties mostly add new abilities for enemies that drastically changes how battles are thought of and how they are fought. Normal allows for more easier experimentation with the mechanics for a better understanding, while the harder difficulties will be very punishing for letting your guard down. They are very different beasts than the normal difficulty.
There are over 14 main endings in the game. You will not be able to experience everything in one playthrough, it's impossible to. In fact, you would have to do many different playthroughs to experience everything. Do what you can with your choices, own up to them, and have fun.