Before you leave your lab try to establish a relationship with the PI such that after you've proven out your technical skills they can write you a letter of rec

Before you leave your lab try to establish a relationship with the PI such that after you've proven out your technical skills they can write you a letter of recommendation as to your general work ethic etc. A recomendation from an established technical professional can go a long way! As others have mentioned if you have the opportunity to write software for the lab as well that's a great first step.