What are effective medicine for psoriasis?

I have psoriasis on scalp and body. I have found betamethasone valerate cream and aminocide helpful. Dovobet ointment I found helpful, but its expensive and all these medicine quickly become less effective.

I found bethamethasone valerate scalp solution to be really effective and its easy to apply.

I saw there are some OTC solutions. They are either salicyclic acid or coal tar. Salicyclic acid seems like it barely works. I guess it helps lifts scales, but causes irritation? Coal tar I have not tried, but I am interested.

Please share anything you found that was effective and its form (cream, ointment, steroid, oral, phototherapy). Anything ineffective is useful too.