My tips, if you have just started to play CS:GO, are here:
Don't plunge you directly in the multiplayer mode! Your opponent may have more experience, and you can be thrown out of your team!
Do the weapons course! There, you can choose weapons, which you could use later several times.
Play offline with bots! There, you can test your reflexes. If you should die, you can pick a bot and take control over him.
No bots: Just explore the area and find some hiding places. Here, you have infinite time.
Only change the difficulty if you are sure that you have no problems in the present!
If you're ever ready, you can go into the multiplayer mode! But you have to be absolutely sure! Maybe, just maybe, you will be prepared and offer your opponent a challenge!