For Onpage SEO
1.Install Yoast SEO Plugins. This plugins is necessary for your onpage SEO. Use good title and description on each page. Use noindex for tag pages, some wordpress themes tend to make duplicate content issue when tag pages being indexed
2.Use light or SEO optimized wordpress themes. Your wordpress themes not only need to looks great but also to load fast. Site loading time is important factor for ranking. Try this to check your site: PageSpeed Insights
3.Install cache plugins. There are a lot of plugins for this. I usually use Quick Cache (Speed Without Compromise) to make my site load faster.
4.Install Sitemap Plugins. I use google xml sitemap. This will make google index your site more accurately. It also help when you are submitting your site to google webmaster tools.
5.Install interlinking plugins. Using interlinking plugins like WordPress › SEO Smart Links " WordPress Plugins will automatically link between your blog post, good for onpage SEO.
For Offpage SEO:
1.Sign up and register for authority web 2.0 sites. If you have a brand name for your site, register your brand on web 2.0 site like wordpress, blogspot, tumblr, facebook fan pages, and twitter. Don't forget to put some content with a link back to your site. Authority web 2.0 sites tend rank easier on google, and it will also send some traffic to your site.
2.Guest post. Try to find a authority blog on your niche and ask if it's possible to put your content on their site. This is one most effective SEO method, a link from high authority sites will give you a referral traffic and ranking boost on google at the same time.
source:www.quora.com