link building advice

i seen afew comments on here saying by building links to post categories the link juice will pass down to posts is this true? or is it better to build links to each post?

It works in both.
If you can get many links for each post means you can go ahead.

But make sure you are not throwing any spammy links for increasing the backlinks.
Consider you have 200 posts under 5 different category you have to get many links. That is not possible when you have many tons of posts on your site.

If your internal structure is good means you can easily pass the link juice to all you post.

Randomly building few links to category pages will always helps. When your site is having more posts then good internal linking structure will get max. possible rankings.

Better to build link to page you want to rank.