Some common intensifiers are somewhat, surely, highly, certainly, very, really, extremely, quite, such, extraordinarily, and tremendously. There are others, but these are a good start if you are new to using them.

This is an extremely unusual bike.

The word "extremely" is an intensifier for the adjective "unusual."

I highly recommend the bakery we used for Heidi's birthday cake. They did a great job.

That's quite an unusual color for a house.

Click here for a video that explains how to use "quite."

We surely got a lot of snow last night.

Setting a mousetrap with cheese is an extraordinarily good way to catch a mouse.

Ted's girlfriend, Linda, certainly is beautiful.

This YouTube video explains the differences between the words "certain" and "certainly."

In each of the examples above, the intensifier can be taken out of the sentence without changing the meaning very much:

Ted's girlfriend, Linda, is beautiful.