If I use subdomain with Wordpress will that affect my main site - SEO?

I want to start a blog, has nothing to do with my original domain, but I thought I could use a subdomain so I dont have to buy another domain.

Will this subdomain mess up my orinal site’s SEO?

I dont want people searching for my [noparse]www.mysite.com[/noparse] and they find blog.mysite.com

Any ideas, thoughts, other options?

If people are going to search for the content rather than the branding then you should be OK. I have several websites hosted on the same domain (just in folders, not even subdomains), and I’ve never noticed any trouble with Google getting confused over the different sites. But then I have people searching for the content and not for “MySite”, which helps.

A good tip would be to include a <link rel=“home” href=“…”> tag in the <head> of all of your pages, giving the URL of the relevant home page, ie the www or blog home page. That will help Google to differentiate between the two sites even more easily.

First it demand on the nature of your site.secondly i will answer your question “Yes” it help alot.This is best practice to grow your site traffic. This process is really liked by Google, running own site blog and it also help user to understand your product more easily. This practice also help you indexing your site fast.