You can't ignore them since they change the pronunciation (most of the time) and the meaning. They are like real letters.
- Some words just have letters with an accent so you have to learn and write them like that:
du = some; dû = due (pronunciation doesn't change)
a = has; à = to/in/at/etc. depending on the context (pronunciation doesn't change)
mais = but; maïs = corn (pronunciation changes)
- The past participle for the first group verbs always ends with a -é:
manger = to eat
je mange = I eat/I'm eating
j'ai mangé = I have eaten
The pronunciation between mange and mangé is not the same.