In math italicize single Roman letters that are variables or functions (example, x,y,f(x),t 2. Exception to above is capital letters for points like P and Q in geometry. 3. Do not italicize Greek letters (example, alpha, gamma, beta, etc..), and units like sec or rad, or punctuation like ( ). 4. Styling the control labels is optional. 5. Do not use strings with <> for such formatting. Use Row[{ăăă }] 6. put () around units in plot labels. As (sec) or (hz) 7. do not italicize function names longer than one letter. So Style["exp",Italic] should just be "exp" 8. The t in delta(t) should be italic--but not the delta, Greek letter are not Italian letters is how I remember that. 9. Log should be log. 10. Is j^2= -1? Better say so in the caption for non EE.
see also http://demonstrations.wolfram.com/guidelines.html
I made small copy here so I do not have to keep looking for this all the time.
To put label on plot, example
To typeset math for display on the demo use this type of coding
Text@Style[TraditionalForm[HoldForm[Sin[x] + Cos[y]], 12]]
To add invisible space use ESC is ESC