I am getting lots of spam after I have switched to wordpress

Spam! It is part of wordpress hosting or something I am missing.

It looks spammers like self hosted blog.
Earlier when my blog was on Blogspot then I rarely got any spam.

If someone of you know how to best avoid spammers reach here, please write comments. I am using Akismet. But I do not want spammer come to my site. So, I am looking for the solution to tell spammers that you are not welcome here. Thanks in advance!