Changing from Weaver II theme to something new. Advice?

I have over 200 blog posts in my site developed 4 years ago. Now I want to be able to redesign my site myself without losing my posts, tags, etc. Most themes seem easier to restart than redesign with drag and drop etc and plenty of online help. I have loaded Page Builder and Visual Composer. Is there a theme or key words to make the transition to a new design easiest for a novice?