Tips to improve pf

hi silly question but has anyone any tips for improving pf trend mine had steaded on pred and was low but stable but now been off pred for 3/52 and pf trend bk on downhill slope am getting days where am pf is only 230 b4 dropping in pm. really don't want to end up bk on pred as struggling to lose weight put on between christmas and middle of April cause best pf is 400 but chest constantly tight at mo and gets worse as day ggoes on even overdosing on ventolin. got appt with costa asthma nurse week mon bt anytips till then gratfully recieved.