The most important thing is to put in the ester oil, otherwise you will mostly likely lose the compressor.
I have found that one of the downsides to the kits is the cheap adapter fittings leak quite often. If you go to aircondition.com they have brass ones that are much more substantial.
I agree with Mr. Carter, the a/c posts are rapidly coming to an end for this year. Even in Texas we are almost ready to get out the sweaters, it has been 71 degrees or less every morning this week when I got in the car. But don't forget to get those A/C's tuned up before the first hot day next year.
Have a great day,