For contact prints:
1) pick a negative carrier and elevation for your enlarger that will project a lighted area that is big enough to cover your negative and paper with room to spare. Record/mark that elevation and carrier and the focus setting you are using;
2) If you use VC paper, start with the setting or filter you use for average contrast;
3) Stop the lens down to about 3 stops smaller than maximum. Record that setting;
4) Do test prints leading to the minimum exposure required to just get maximum black through clear film. Record that exposure. It should be somewhat close to your 10 - 15 second timing (if those prints were also done at 3 stops below maximum);
5) Now do test prints with your particular negative, to fine tune that particular print. If possible, you should start out with something you might consider an "average" negative.
If the fine tuning requires big changes as to contrast and exposure, you may need to adjust your "standard" starting point to make subsequent negatives easier to deal with.
Contact prints look subtly different than enlarged prints, so don't hesitate to experiment a bit until you get a "standard" look that you like.