Janmashtami Puja Vidhi in PDF, procedure of Sri Krishna Puja on Sri Krishna Janmashtami (Gokulashtami) to download in PDF format is given here.
Here is the detailed Janmashtami puja procedure with mantras. This Krishnashtami pooja vidhi article also includes the list of items or material required for Sri Krishna Gokulashtami Pujan.
There will be slight differences in steps involved in Janmashtami puja procedure from place to place (South India & North India), but the generalized puja vidhanam is given here. In 2018, Janmashtami date is September 2|3.
The Shodashopachar Puja (16 steps of Puja) is given here with all the needed mantrams.
Check this video for detailed Janmashtami Puja Procedure with Mantras and fully explained Puja steps..
Download the PDF of Janmashtami Puja Vidhi, procedure – Link