You want an agent? Ok. Now work backwards.
What do you need to get an agent? Talent, communication, headshot, résumé, cover letter, labels/mailing list. If the agent already knows you, you would have an advantage.
The most important thing in that list is a résumé, because it shows what you have done without you actually being present to tell the story.
So how do you create a résumé that’s going to be interesting enough to get you an agent? By getting some interesting work to put on the résumé and by working on reputable projects with reputable directors in reputable production companies.
What can help you get work? Or rather what will make casting directors want to hire you? If they see that you are well-trained and can take on the roles for which they are casting AND if you are right for the parts AND if you are better than the other candidates or have something to offer that is different or more interesting than your competition.
What will help you be seen as a well-trained actor who is the right actor for roles and who is better than the other actors they see? Training with a good school and a good teacher.
If you have not been training, I think your time will be better spent building a base of SKILL first before looking for an agent. Remember that casting directors and agents eyes are trained and experienced and they can see when an actor is trained or not.
Now that we have gone through that, here is a way that you can use to get an agent: Get an agent.