Parking during test

What is allowed during the parking in the drive test?

Am I allowed to open the door and look at the lines to check if I am in between the lines and then have another attempt to straighten the car?

Any other tips?

Yes you can open the door to see that you are right

Of course it’s allowed to check the parking from the outside. But use it only as the final measure of your parking when you already feel that you got it right.
Learn to use the side mirrors properly when when reverse parking, don’t rely on the reverse camera or just looking backwards. That will make it so much easier.
Of course, when doing any reverse driving it’s important to check your surrounds frequently and don’t rush it.

Also, learn all the guidelines for different kinds of parking fluently. Practice them over and over again. That was my main mistake on my first driving test. I knew how to parallel park in theory, but I had not practiced it enough. When the test nerves hit me my head went blank and I messed it up completely. I made sure to practice it to perfection before the next test. I never got to do it again in a test though, but now I feel more confident parallel parking regardless.

Thank you everyone for your wonderful response.

@ RiverOak, failed test because of not good parking? How big was the mistake that this happened?

Oh, it was terrible! As I said my head went blank and I couldn’t for the life of me remember how to parallel park. It didn’t help that it was a really tight spot on cobblestone where I couldn’t see the curb properly. My friend who has been driving for 20 years and is a good driver said that he would have had trouble parking in that spot. So it wasn’t a very nice choice of the inspector. I eventually gave up and we continued the test. Failed for lack of manoeuvring abilities, obviously.
The next time I parked perfectly right away. I was actually surprised at how well I did. I was directed to pick a parking spot and park any way I wanted. I chose not to safe it and picked a pretty tricky spot and backed into it.