Taking part in drama doesn't always involve learning lines from scripts - often you'll be asked to improvise. You'll need to be able to think on your feet and 'become' a different character.
This might sound difficult, but you've probably improvised before without realising it, eg in games you used to play as a child. If you ever played pirates, nurses or superheroes when you were younger, you were improvising.
There is much more to acting than just reading a script out loud. If you're nervous, it's tempting to read the lines really quickly, using the same tone of voice all the way through. This isn't very interesting for your audience.
Try to think of punctuation as musical notes telling you when to pause for a breath and then to add emphasis after the pause (for dramatic effect). Don't be tempted to take a little break at the end of each line - the piece might not make sense.
Do keep in mind, however, that a pause of even just a second will likely seem an eternity to you but will be perceived as entirely natural by your audience. Use pauses effectively.
Read the script from Romeo and Juliet below, pausing at the end of each line. Then try again using the punctuation as your guide for when to pause.
Think about how changing where the silence is changes the meaning of what's being said. Which way do you think works better?
The clock struck nine when I did send the Nurse;
In half an hour she promised to return.
Perchance she cannot meet him. That's not so.
O, she is lame! Love's heralds should be thoughts,
Which ten times faster glide than the sun's beams,
Driving back shadows over lowering hills.
Therefore do nimble-pinion'd doves draw Love,
And therefore hath the wind-swift Cupid wings.
Now is the sun upon the highmost hill
Of this day's journey, and from nine till twelve
Is three long hours, yet she is not come.
Had she affections and warm youthful blood
She would be as swift in motion as a ball:
My words would bandy her to my sweet love,
And his to me.
But old folks, many feign as they were dead -
Unwieldy, slow, heavy, and pale as lead.
Using the punctuation as your guide makes it sound like a real person thinking aloud.