If you are approaching the time when your car insurance is coming up for renewal, give yourself plenty of time to shop around for quotes before it automatically renews. Most policies automatically renew the day they expire and you may find that you cannot cancel online but instead need to call someone to cancel the policy.
If you do not mind who you use for your insurance then you may want to use a comparison site such as Money Supermarket or Compare the Market to find the best prices for you. Not all insurers advertise their prices through these sites, so if you really want to find the best site then you may also need to check directly on other insurers websites.
If you want to try and earn a bit of money back on your insurance policy then you may decide to use a company such as Quidco or Top Cashback to see what they are offering. The cashback is not guaranteed, but as long as you meet the criteria, it is often paid out. Some people use the comparison sites then use a cashback site to complete the purchase. Always be careful when doing this as some insurers will not pay out cashback if they have provided you with a quote through a comparison site first. Make sure when using a cashback site that you clear all your cookies and ideally use a different email address to the one you use on the comparison site.