Be sure the suction or cool line from the condenser to the compressor is insulated with snap-on urethane or other high R-value insulation.
Straighten all of the evaporator and condenser coil fins with a small pointed stick or a special plastic fin comb. Bent fins do not allow proper air distribution.
If the condenser is at ground level, be sure no vegetation or foreign material is restricting the air flow path. If possible, shade the condenser with trees or bushes, which will improve the cooling efficiency by elimination of direct sunshine.