It is most likely your injection method. I never get pip. I used to when I was using some aussie T400 many years ago, But very seldom any more. The way I have been doing it is push the pin in quick and inject quick. I haven't aspirated in probably 15 years and have never had a problem. If you are leaving the pin in and injecting slowly, you may be moving the needle and damaging tissue which will cause pip. Since you are new to this you are probably tense as well.
I keep it simple and make it quick. No pip. That's about as much advice I can give you. I don't understand all the pip I hear about.