Help/suggestions from TUMBLR blog premium theme designers....

Hello, I direct a nonprofit agency and wanting to now purchase a “premium” blog theme to upload and use from within my Tumblr account. The problem being that I am very new to this, I really am not certain what blog features that I need, all I know is how I want it to act. Having said that and being without the technical know how of what to purchase/who to purchase on here from, I am casually taken suggestions/comments to this post on what I need to consider from a technical stand point. Please advise as you can - no rush. Email/private me direct if like. Good day to all.

Hi There,
please see our portfolio:
i am a tumblr developer. i have tumblr theme for blogging and business.

btw, i also availbale for custom tumblr project from scratch.

you can contact me via email if you interest.