what type of index should i create?

I have table name as table1 has 6 columns. and i am performing 3 type of select operations against this table.

select * from table1 where col1='something' and col2='something'

select * from table1 where col3='something' and col4='something'

select * from table1 where col1='something' and col4='something'

I across many forums that multi column index is better in performance wise. so in order to create multi column index ? in which type i create index for the above scenario ?

create index1 for col1 and col2 create index2 for col3 and col4 create index3 for col1 and col4 like this ? or any idea for optimized index creation to increase performance ?