So I guess I can give you a bit of input generally speaking.
If you’re very new to the game, you may not know that you need to long rest regularly at camp to replenish your spellcasting powers. You’re only going to be stuck with your weakest spells if you don’t long rest after every couple of battles (especially in the early game). If my most powerful spell was firebolt, I would lose every battle, haha. It WOULD be frustrating. In fact, I didn’t understand the long resting mechanic at first.
Second, some spells are way better than others, and it’s important to know what to pick for each character. For example, sanctuary (cast by a cleric) is an absolute lifesaver, and I have come back and won many battles as a result of that spell. If you’re interested to know which spells I think are strongest for the different casters, I’d be happy to tell you.
Third, I think it’s important to always have one tank character, who can deal decent damage in the beginning of the game and soak up some of the damage dealt by enemies. Lae’zel as a Fighter, or Karlach as a Barbarian, would work well for this. I personally think that a team of four spellcasters is pretty weak in the beginning.
Fourth, you can actually avoid a lot of battles by playing as a character who has high charisma. I absolutely love playing as a bard! I’ve talked myself out of so many sticky situations and saved my own life several times over, I’m sure. You get the same amount of XP for talking yourself out of a fight as you do for actually fighting.
Fifth, if you know what’s coming in a fight, ungroup your party members and strategically position them for best results, so that they aren’t all grouped together as a huge target for enemies. That way, not everyone will be killed by one area of effect spell.
I normally play as a spellcasting college of lore bard (with one level of cleric for medium armor, shields, and the sanctuary spell), then I’ll have Shadowheart as a cleric, Lae’zel or Karlach as a tank, and then either Astarion or Gale as another spellcaster. I like to respec Astarion into a bard, and having two bards actually works pretty well for me. They have an ability called cutting words, on the college of lore route, that decreases the chances that an enemy will hit a character. Gale has some awesome spells but I do think I prefer bard over wizard.
