Check out this information + practice by the BBC. Click here.

Do some exercises here, here and here.

To practise even if and whether, click here.

Try inversion exercises here and here.

Warning: ignore inversion of the second conditional in for the time being, but you'll find examples in the exercises above. If you still want to know how to do it, here's how (scroll down).

Using linkers wisely will make your writing more readable. Try some exercises:

Practise the use of discourse markers: click here, here, here and here.

To practise different kinds of linkers , try the links below:

Combined linkers here. This one is a multiple choice exercise.

Find purpose, reason and result clauses here.

Expressing reason here.

Expressing purpose here.

Expressing contrast here.

And if that's not enough, you'll find plenty of exercises here.