This is like asking if your nostrols are suppose to be wet or completely dry. Generally the tip is usally dry, (just like the end of your nostrols are usally dry). Sometimes if the penis tip is wet, it can be normal, but usally it is dry.
After you urinate its normal to have clear discharge,
After you perform the valsava manuever (using the toilet to excret soild wastes) is also normal to have clear discharge
After you ejaculate is normal to have clear discharge.
Before you ejaculate its normal to have clear discharge.
In the morning its normal to have clear discharge (due to morning wood).
Usally the tip has to be dry druing the day or before you urinate during the day.