There doesn't have to be a set structure for language coursework - you can do it in any way you like, providing it meets the baseline requirements. And I think it has to be a minimum of 250 words if you're doing higher tier.
You could perhaps start with a brief introduction, saying what you currently study (ie GCSEs), what your favourite subject is, what you're planning to do for A levels etc. (this is present tense & opinions!)
You can then go on to talk about your ideal job - first, what kind of job is it? (this is description & present tense). What are your reasons? (opinions, perhaps modal verbs used) Are there any negative aspects to it? (opinions again! Perhaps the conditional can be used here) If you can, you could perhaps add an anecdote or something which made you want to pursue that career - then you can use the past tense.
Basically, GCSE language coursework is about ticking boxes So make sure to include:
* Opinions: meiner Meinung nach.... ich glaube, dass... es scheint, dass... man kann sagen, dass... aber ich denke, dass.... etc.
* Modal verbs: ich will... ich möchte... ich muss.... ich darf... ich soll...
* Different tenses! This is vital. Try and use the present, future, past, and maybe conditional (ich würde...)
* Connectives & complex sentences: using weil, und, aber, obwohl, also, deshalb, jedoch, sondern... snazzy words like vielleicht, wahrscheinlich, allerdings, leider, am liebsten...