Temporary Work (skilled) visa (subclass 457) (Sydney)

Hi everyone!

I am 26 and I plan to move to Sydney in October this year. I completed my Masters in History and I am currently doing a traineeship in a photo library.
I would like to apply for the Temporary Work (skilled) visa (subclass Protected content I will need to be sponsored.
I have a few questions related to that:
- Do you recommend that I submit an expression of interest on SkillSelect?
- Would you have any pieces of advice on how I could look and apply for a job in order to be sponsored?
- Would it be helpful to contact a migration agent?
If you have other tips related to that or if you have had a similar experience, I would be glad to hear it.
Best wishes,

Coralie