Giving an opinion
The phrases that introduce what you think, and the ones that place it against someone else's.
Saying what you think
| je pense que … | I think that … |
|---|---|
| je crois que … | I believe that … |
| je trouve que … | I find that … (a judgement from experience) |
| à mon avis, … | in my opinion, … |
| selon moi, … | according to me, … |
| pour moi, … | for me, … |
Que is not optional after penser, croire and trouver: English drops it ("I think it's true"), French does not — je pense que c'est vrai.
Agreeing and disagreeing
| je suis d'accord (avec vous) | I agree (with you) |
|---|---|
| je ne suis pas d'accord | I disagree |
| vous avez raison | you are right |
| c'est vrai, mais … | that's true, but … |
| ça dépend | it depends |
c'est vrai, mais is worth more than it looks. Conceding before disagreeing is what makes a disagreement sound reasonable in French, and an examiner scoring interaction is listening for exactly that move.
Preferring
Je préfère A à B — with à, not que: je préfère le train à la voiture. And j'aime mieux is its everyday twin: j'aime mieux le train.
One thing to know but not yet use. In the negative, je ne pense pas que is followed by the subjunctive — je ne pense pas que ce soit vrai. That is week 25. Until then, disagree with je ne suis pas d'accord and stay in the indicative.
Knowing the rule is not the same as producing it.
This page explains the pattern. The track drills it: the point arrives inside a mini-dialogue, then production marked against a CEFR descriptor, then a module test that returns you to your two weakest sessions if you miss it.