Query Tuning techniques basics in details

Hi All,

I am working on query tuning tasks. I have studied few documents and presentations, which talks about methods to write a optimal query. The documents are ppts are say the below things briefly:

1. Usage of exists clasu instead in clause (where ever it is applicable)

2. Avoiding unnecessary usage of distinct/order by clauses in the query

3.  Order of the tables in the FROM clause of the tables.

4. Order of the join conditions in the WHERE clause and the like.

But, I heard from one of my senior DBAs that "Order of tables in FROM clause and Order of join condition in WHERE clause" are not important now as from 10g onwards optimiser will take care about those things.