One of my blog site has 200+ internal links. Is this against SEO? should I do all internal links "NoFollow" ? give me tips.
I assume you mean it has 200+ internal links on each page (or at least one page). If so, that is a bad situation for seo. Search engine spiders typically have a limit of how many links they will follow on each page. I think some have a 50 link limit and others may have a 100 link limit. I'm not positive on those numbers, but it is still best practice to stay below 100 links per page. Many websites do choose to use the nofollow attribute for internal links, but not for all of them. You still want to be able to spread your link juice throughout your entire website. You may be able to add nofollow to less important links such as a contact page, privacy page, terms & conditions, etc. In your case, I would move the 'list of jokes' menu to a sitemap page or something similar. You could still use a drop down menu to be able to navigate to those sections or you could add nofollow to all of those specific links.
There are plenty of tutorials about onpage optimization. The key to it all is ensuring that search engine spiders can properly crawl and index all of your pages. You could put your keywords in important page locations and do other things like that, but none of those things will give your rankings. Rankings all comes down to backlinks. Enough quality links can make any page rank well despite how bad their on-page optimization is.
I read in different places that if you have alot of links on one page it may look like a link farm. this may be an issue.
Google suggests to keep the number links under 100 on single page. But even more links shouldn't hurt your SEO. On the other hand why not to create 2 pages with 100 on each one? Think about the users -- if it will be better for users divide the links between 2 pages otherwise let it as is.
What is the purpose of having hundrends of links on a page. No one will click them. The point of internal linking is to create a usable navigation system. You can control to some effect the internal PR, but you are going to be wasting a lot of time doing this in a blog. Just use Google Webmaster and then work on creating incoming links.
It really depends on the size of your site and your navigation structure. I have a site that has over 300 internal links from the home page. The number of links are necessary to support a structure that can access the hundreds of thousands of pages on the site. Visitors to the site navigate from the home page down to the next level without any visible problem (bounce rate is low, people visit 3 to 5 pages on the site, etc.) The site ranks #1 for the main keyword in it's niche. Most of the second level pages (the 300 links) rank in the top 10 for their keywords. The search engines seem to have no problem with the number of links on the home page. My advice is to build a structure that you think will work for your site's visitors and don't worry about how many links it takes to do it.
You can pass pr up to a specific page on your own site by using a strategic link method involving just your own pages. It's one of teh reason the old 10,000 page spam sites were so popular. Nowadays, it still works, but the links need to be created over time in a natural way, and if it's too blatant it triggers a filter.