You can add a wide variety of bonus effects to your party by equipping roles to characters. The two types of roles are unique ones that certain characters have from the start and ones every character can acquire if a certain combination of skills has been sparked.
Check the Battle Difficulty
Make sure before you start a battle you check its difficulty to get an indication of the enemies' strength. The classifications Easy, Normal, Hard and Very Hard.
Expand your Team
In SaGa: Scarlet Grace the choices you make during the game affect which characters can and cannot become party members. Adding characters is beneficial as it will give you new party formations when they join your party. The only time you will not be able to accept the assistance of a character is when two characters can't be party members at the same time.
Formations
The formation and positions you select for the characters in your party affects their starting BP, BP regeneration method, stat adjustments and other boons they may have. It can also open up benisons which can be very useful during battles. If there is a particular party you want to use try experimenting with its formation until you get one that works.
Manually Save
Although SaGa: Scarlet Grace automatically saves between engagement waves it is advised that before you do something that may heavily impact your game you manually save it to ensure your progress up to that point is saved.
Party Protection
If you have two guardians in your party it will help protect against enemy attacks that target all party members as each guardian is able to protect one other party member, potentially reducing damage by 60%.
Read the Situation
Most fights will hinge on your ability to read the situation and act accordingly. Although brute force will usually accomplish your objective it can actually be quite a bit more advantageous to buff/debuff and play to the various mechanics of the game.
Using a Bow or Axe
If you want a character to use a bow or weild an axe they will need to have high DEX to reliably hit with either weapon. Don't equip a bow or axe to any character unless they have over ten DEX.
Bonus Effects...