Type 1(real present): If + any Present Tenses, will(may, must, should) + bare inf
Type 2(unreal present): If + Past Simple or Continuous, would(could, might) + bare inf
Type 3(unreal past): If + Past Perfect or Past Perfect Continuous, would(could, might) + Perfect inf
Mixed Conditional:
Type 2 + Type 1
Type 2 + Type 3
Type 3 + Type 2