i am currently using h1 and h2 tags, but was wondering if there is a specific H tag that google looks at most?
I beleieve google will look first for H1, then H2 and so on... Those are used to structure content, as H2 should be a subtitle of H1 and so on with H3 and H4...
That is correct Header tags should be used in a structured way. You would not have H4 if there are no h3, h2, and h1. More emphasis is given to h1 over 2-4 just as more emphasis is given to h2 over 3 and 4. Main headers are h1. Secondary headings within h1 would be h2 and when and if there are any further headings within the h2 they would be h3 etc. Every page should at the least have h1(s), but only use h2 through h4 when neccesary for the content
From my studies of google, they give more weight to Bold, Under Line and Italics tags and Red Fonts more than H1 -H4 tags.
Im not sure if they give more weight to those, but I am sure that these are great methods (if not over used) to increase the SEO of your pages. Very good advice
To get better result, you may combine Hx tags with <b></b>, <u></ul> or <em></em> in heading or other texts.
Use header tags for titles, I see these is their proper use, don't use them on emphasizing keywords within the paragraphs.
I do not think google reads the CSS but maybe. I would have to say no. I have never seen googlebot spider my CSS file. Which tells me they probably ignore CSS all together. I may be wrong though.
That is incorrect. Google doesn't give more weight to bold, underlined or italics text. It might give more weight to semantic elements such as strong or em which are used to describe meaning of the text, but physical elements such as b, u, i only control physical appearance and flow of the text and very likely have no importance in SEO. Color is also just a physical attribute and has no semantic meaning - thus it's irrelevant SEO-wise.
I beleive that A H1 is the most important and also using the H-tags in order is a good way of optimising. The order of content should be most important to the least and the H-tags should reflect this.