Editorial style guide - R
Use an en-dash with no spaces either side:
students aged 21–30
3–8 Palmerston Road
Cut out words that don't add anything to the meaning of your sentence.
You can register now, or alternatively wait until July.
Pip is the chief protagonist of Great Expectations.
Sometimes a word can seem necessary but you might find you can do without it:
The charity raises money to buy vital equipment.
See also Tautology