How to change old urls safley?

I have been searching this for a while and haven’t found any answer to it.

Due to not knowing anything about seo I mad lots of mistakes when optimizing my posts (titles-urls) in the past. Now I am trying to go back and fix the problems. But, I am afraid to do so, because of the seo effects.

Is there any way to change old urls and titles with a plugin or what have you that wont result in losing traffic or getting a 301 error? And does changing urls to a better seo optimized one have any positive effects? (By the way, I am on WordPress)
Thank you all in advance.

Set up 301 redirects in the .htaccess file to tell everyone that the change of URL is permanent (temporary changes should use 302).

The URL will have almost no effect on SEO as long as the search engines can find the page.

Thank you for the reply Stephen. This would work if it was only a few urls, but I will have to change a lot of urls. Is there any plugin or any easier method to do it since I will have to do this for lots of pages?
Thanks.

If there are a lot of them that are similar then you might be able to catch all of those with a rewrite in the .htaccess that can match all of the old and corresponding new names using a pattern.

although it takes time to get the pr back…

Once again thank you very much for taking time to reply. While looking around I found a plugin(Well, I didn’t just find it, I was using ti but didn’t know it had that function as well) that does exactly what you suggested, automatically. So, I don’t have to worry about changing urls anymore. Its the platinum seo plugin. I guess I just have to click one option in the settings and it will create the 301 automatically, every time I change a url.

Anyway, thank you very much for your help. I really appreciate it.

I have done some reading and Haven’t found any evidence that points to loss of pr.

URL will not effect on seo point of you as long as you have your titles… example :http://example.com/page_title.php?id=49