I have no idea what I just read here. I assume you mean pre-filter with cotton before using a micron? If you meant just using cotton/cig filter without micron then that's a recipe for disaster.A pre-filter with cotton may somehow do the trick better as will not leave you that much with a clog. We also have a thread in case you wanna learn more made by the fat pirate, @Captain.Heroin. In other words you can try tobacco filters. But I think you are a beginner since you ask this and there's no shame but for every syringe depending on country should have a built-in filter, as far as vials isn't diffcult, just buy some Diazepam or anything from pharmacy that it's stored in vials and that's it, you can sterilize it home or basically just go to a barber shop and ask him if he wants to help you. If you have any other Q feel free to ask.
Also "just buy some diazepam"? Where on earth can you just buy liquid Valium at the pharmacy?
Also asking a barber to sterilize stuff?? They're not trained in sterilizing stuff meant from injection. Barbasol isn't meant to be used in injectable prep environment.