I am 54 year old man my sex life is good but I know it can be better. I had a vasectomy done few years back what can I do to improve my sex life?

Exercise, eat right . Vasectomy has probably nothing to do with it. If libido is issue check testosterone. If function is issue see doctor. Eating right and exercise will improve blood flow which makes everything work better.
What's not right? Sexuality is complex. If you aren't having erections - or if your erections aren't strong enough - there are medications available. If your sexual desire isn't optimal, take stock of issues like depression or overall health concerns. You might ask about getting a testosterone level checked. Are things going well between you and your partner? Ask your doctor for a referral to a sex therapist.