As a layman, it is not possible for you to do a proper new homes snagging. You need a qualified professional to help you spot some of the things you are likely to miss. Here is an outline of the purpose of a professional snagger.
Checking for defects in the tiling, glazing, paintwork or woodwork. They basically look for things such as scratches & chips, paint splashes, and cracks in the ceiling and walls. With the help of a spirit level, they also try to find out if the surfaces are level enough.
Checking for proper fitting or screwing of all the things that need to be built in that manner. A simple thing like whether the water in the tap is running properly is also part of the work that a snagging inspector would do.
Reporting any of the noted defects to the developer of the property so that they can be corrected before buyers start viewing it. Apart from that, they leave sticky notes where the defects have been detected to ensure necessary action.
If you are a property developer worth your salt, there is no way you can avoid new-build snagging. Engage a qualified snagging inspector to help you improve your property before putting it out for sale.