Ok so a few pointers when looking at your insurance...
General insurance - Many companies are Underwritten by insurers, some companies are underwritten by many insurers making them brokers eg, Lloyds TSB or Halifax ETC.. So when looking through quotes check the underwritter.
Renewal - Keep in mind when your renewal date is due, as looking in advance on comparison websites can save you up to £150. Rates change constantly so if you save a quote on the 1st jan for the 30th it might be £500 whereas if you look for quotes on the 17th for the 30th it could be £600.. so planning ahead can save you lots (I did this for S3 Rav and he found cheaper rates in advance)
Fresh quotes - comparison websites look through different companies or brokers who give you the best price within your demands and needs. When inputting your data check a few things such as
Marital status - Saying your single can increase your risk, If your married then it may reduce your premium especially if you add your Mrs to your policy can reduce your premium drastically. If your partnered or co-habiting it can also reduce the risk and premium so play with your options.
Use of another Vehicle/ home owner - This can reduce the risk of your policy simply because you have driving experience of another car/ you own a home which shows your financially stable (somehow) therefore reducing your risk.
Occupation - this Really does matter... Your occupation (no matter how professional) can really affect your premium. Saying your a chef can increase your risk.. If your an cook however can reduce that risk. think of the many options that relate to your job title and see the price difference. If neccesary go back and chose a different occupation to see the premium change.
Claims and convictions - dont lie! Lots and lots of companies use the CUE system which is the Claims underwriting exchange. Its a database of claims youve had and they check this often.
Car purchase date - the longer you've had your car, the more experience thus lower premium sometimes.
Regular driver - This is the person who earns the NCD.
Additional drivers - adding other drivers can reduce your premium. I had my mum and bro in law on mine and because they are seen as more experienced, it can lower your premium. If your married, then get a quote with your wife/husband on the car as it can half the risk and sometimes the premium.
Mileage - On comparethemarket.com the 4000 mile mark seems to be cheaper than other options. sometimes when you lower your mileage it can increase the risk somehow, so play with the option.
Night parking - Now this can play with your premium alot. Depending on where you live, if you select public road it can be cheaper then selecting "Garaged" so again play with this option so you can determine the best option for you.
Address - Risk address can really affect your premium depending on claims made around your area and underwritting risk assesment in your area (crime etc). If its expensive, its time to move lol. generally if you live closer to the city centre its more expensive. EG. CV1 is more expensive than CV6. this May not apply all the time though.
Theres some things you can look at, if i remember any more then i'll add to it but one thing.. Please do not make obvious lies on your policy because you can be caught out and wrong information on your policy could void it. so if you had a claim and they find out that you have had a claim/conviction or that your not the regular driver of your car then it can repudiate your claim!! The above is only an advisary on what each option means.