Most of the Blogger start with a blogspot blog, and later on they move to wordpress. Many of them migrate their blog to wordpress and some of them leave blogspot blog behind.
If you are migrating to self hosted wordpress blog and keeping the same niche best advice will be migrate your blogspot to wordpress.Though in case if you old blogspot blog does not fit your new niche, instead of leaving it like that, you can use it to drive some traffic to your new blog.
The idea here is to divert all the traffic from a blogspot blog to your wordpress blog and enjoy the traffic .
To do this , you need to edit your blog spot template. Go to edit HTML and search for following line :
<b:include data='blog' name='all-head-content'/>
Now add this piece of line after the above line
<meta content='0;url=http://www.shoutmeloud.com' http-equiv='refresh'/>
Replace Shoutmeloud with your blog URL and enjoy the traffic from your blogspot blog , which you left behind.
Though this trick I will suggest to use only if you don’t want to migrate your blogspot blog. If you need help with your blog (blogspot to wordpress ) migration, you can contact me using my service page.