Landing a talent agent is a major milestone for an actor but it doesn't mean the road ahead is paved with gold. One of the pet peeves of talent agents is when newly signed talent sit back and cease growing after signing. That's precisely the time when you should be cranking up the effort and taking advantage of your momentum. An agent doesn't expect a newly signed actor to start booking jobs immediately but they do expect them to be looking for jobs on their own and not leaving it all to the agent.
Talent and versatility are important, but professionalism is vital. You need headshots, resumes, and demos. Plus, you are expected to show up to (sometimes last-minute) auditions and jobs, on time. Striving to improve your skills and therefore your booking ratio is a constant. Top actors (Voice One teachers included) practice and study their craft. If you expect to compete with them, you have no choice but to improve. You need to practice regularly, attend industry mixers, learn new techniques, branch out into other areas [acting, improv, theatre, film], research new trends, and learn new technologies.
Your agent represents hundreds of actors. They submit actors for auditions based on them being reachable, available and the likelihood of them booking the job. You must be easily reachable and virtually always available or your agent won't have confidence in submitting you. You must be always improving to enhance your chances of nailing that audition. If you stop growing when you land your agent, your chances of auditioning, let alone landing jobs, are minimized. If you find you aren't auditioning as much as you'd like, maybe it's time for another growth spurt that will make you more competitive in the market.
Remember, landing an agent should be a milestone on your journey, NOT a destination. Keep your skills sharp!