welcome to the forums. I have heard recently that even beta-actin is not the best control. Many people use alpha-tubulin. What I would do is ask your lab mates or read up on similar papers using the same treatment conditions as controls tend to vary depending on what you are doing to your cells.
Also, antibody manufacturer's want you to use up all your antibody.
Try 1:10,000 that should be enough.
If you want, cleverly run a gel, and transfer to a western blot membrane. Cut the membrane into 3 pieces. Try 1:1000 antibody dilution with one, 1:10,000 antibody dilution with the other, and a different blocking technique with the last piece (1:10,000) ie block also during antibody incubation step.
See what you find
No the beta-actin is present in all your samples, and is usually a standard control (or loading control). You can strip your membrane and blot for this after your initially screen for your protein of interest using your antibody.
Any questions or suggestions please post back here montMolec!