You need to practice working with type in order to become comfortable with the basic rules and develop the necessary aesthetic sensitivity. Short of enrolling on a course in typography or lining up an internship for a printer's or design studio, try the following. Try recreating typographic layouts from the world around you. for instance take a magazine or newspaper and try to recreate a single page of its layout. You will appreciate the craft involved. Observe, and document type in the world around you. Carry a camera, keep a sketchbook. look out for vintage painted lettering, shop fronts, road signage, drain covers, clothes labels, packaging... Try tracing and drawing your own letterforms. Buy a book on calligraphy. Get out that sketchbook and practice. Try some of the suggestions here. Typography. What is the best way to learn how to kern? The first few pages of well-designed book. look at the how the sequence of pages play out and how t relate to one another. What makes a good typographic title page? What makes a quietly effective contents page? Try creating your own. Find a typographic layout and redesign it for a range of different formats. For example, take a square advert, and place the same elements in a narrow vertical column. You'll have to engage with a range of skills. scaling type, and adjusting letterspacing and linespacing.
I usually add in 2–5 pts, 1–3 pt for line break, and 0–3 pt for italics. I generally avoid font weight except for some heavyweights. A few exceptions for the heavyweights: Monotype's “Naked” is used for the body text in my e-books and my books, and a little in the webcomics in my Tobacco Webcomic site. In comics, I avoid using any non-bold, non-italic fonts to conserve space, since many readers don't read a bit of a page without bold, italic text, and with such small images, I just don't make the webcomic look good. Also, I usually avoid fonts that read “dynamic” (like Helvetica), unless it is something like the name of a new character or something where they are important to the story I'm telling. Other characters do use bold, italic, dynamic type, and a bit of line-height. The characters in comics are all “dynamic”. I prefer.