When you start nipple pumping you should do it regularly but avoid overpumping. Regularly means every day for two times. Maybe in the morning when you brush teath, shower (yes, you can) and prepare breakfast for 30 min. And then again in the evening when you watch TV for another 30 min.
You should use smaller nipple suckers (SuppelNipps) in the beginning. You can use bigger ones after your nipples have grown in the next months.
After 1-2 months you will be able to go longer for maybe an hour each session. But you should avoid to pump for a long time in one session or even fall asleep with SuppleNipps still on (which would be possible, because the hardly fall of even during sleep).
When you overpump you can develop water blisters on the nipple or areola. You would experience liquid (sera) in the nipple sucker. This is nothing dangerous but it burns a bit and you should take a break then for 1-2 days. You can see what happens when you develop a water blister here in this NippleCoach avoiding water blisters tutorial video.
When you got sore nipples because of overpumping or too much nipple play you can take care of them with a antibiotic cream. See taking car of sore nipple video here.
It’s fun to find a play or nipple play and pumping partner to compare results and experiences.
Summing up my tips for nipple pumping beginners.
1. Regularly 2. Avoid overpumping 3. Find a nipple play partner