Changing from numeric permalinks to custom

I’m trying to change my site’s permalink structure from:

/archives/%post_id%

to

/%postname%/

Changing it in WP admin is easy, however I’m trying to modify the htaccess so as not to affect our SEO and break older links. I’ve found tons of examples how to do this with all other permalink structures except this one.

Here’s the weird thing. I got it working by adding 1 redirect, however when i add more it breaks the entire site.

Current htaccess:
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^archives/2374$ https://www.g33kpron.com/twitter-infographic$ [R=301,L]
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

This will work, but the moment I add more entries after that one, it breaks everything.

Any ideas?