Volunteering

Volunteering in the emergency services would suppose means to be able to do a job without asking for anything in return and that benefits others. A volunteer must enjoy helping others and be available for emergencies as they arise arising.
I'd like to volunteer in third world countries to help people who really need it. I also would also like to volunteer in organizations dedicated to the conservation of nature and animals.
I would (alt: I'd ) like to volunteer in the first place because (alt: My main reason for volunteering is because ) I like to help people and I'm am a lover of nature and animals. Secondly, I would like to volunteer because I love travelling, and volunteering would mean travelling to others countries.
I hope to someday be voluntary a volunteer because it would be one an unforgettable and amazing experience and satisfactory.

"would suppose" - I'm not quite sure what you meant here.  If I was writing this sentence I would say: " To volunteer in the emergency services you must want to do a job that benefits others without being paid. "  I wouldn't say "nothing in return" as it implies the job isn't satisfactory in any way, but you do recieve personal satisfaction from doing the work.

"satisfactory" - If something is your dream it is wrong to describe it as satisfactory.  This implies very weak enjoyment.  " it would be an unforgettable and incredibly satisfying experience" is much more appropriate.