Are you shaking the polish? This can cause the bubbles. Instead of shaking the bottles, slowly roll them in the palm of your hand to mix the polish.
Keep the coats as thin as possible; three thin coats is better than two thick coats. Make sure you’re not sitting in a draft when you apply your polish. Don’t “work” the polish too much; the fewer brush strokes the better. This might mean getting polish on your cuticles but you can clean that up after with NP remover and a cuticle stick wrapped in cotton but there’s nothing you can do about bubbles. If you’re only using O.P.I., try a different brand. The older revelons bubble on me but the newer ones (the big three free ones) don’t. You may have better luck with a different brand. I think that the reformulated O.P.I.s are hit or miss. You might also try a different base coat.