My personal preference is to use the Edit HTML mode for preparing my posts, and to get a view of how it will display on the Web, I click the link at the top right-hand corner of the post editor, just below the Edit HTML and COMPOSE tabs. Then to resume editing, click the link. The reason I do this is because it gives me better control over how my post will display and also, in the COMPOSE mode, a lot of formatting tags are added, which, when I change to Edit HTML mode to do something, I will see a lot of formatting tags which the program puts in for me which makes editing the post very hard for me. In the Edit HTML mode, I can also add Headings for sections of my post by using the <h2> and <h2> tags. In the COMPOSE mode, I will have to switch to Edit HTML mode to do that. Anyway, if you don't want to have to deal with HTML, you may stick with this option. However, I strongly encourage you to learn some HTML and CSS (Cascading Style Sheet). A very good place to learn that is Learn HTML and CSS tutorial
Post Editor Toolbar in the COMPOSE modeIn the COMPOSE mode, you will get a more elaborate toolbar:
The first tool you get in the toolbar is a drop-down menu to select the font. For example, I want this sentence to be in Arial, I will have to highlight the sentence and choose Arial (the first tool) in the drop-down menu. The following sentence should also be in Arial. If I want back the Times font, I choose Times in the drop down menu, and the sentence will be back to Times, like the rest of the post. You will have 9 choices of fonts - Arial, Courier, Georgia, Lucida Grande, Times, Trebuchet, Verdana and Webbings. Alternatively, you can select your font and font size right from the beginning and the whole of your post will be in that font and font size.
I may also highlight this text and select Huge from the second drop-down menu for font size. You have 5 choices here - Huge, large, normal size, small and tiny. You may also make this word red or any color you like by highlighting the word, clicking the text color tool icon and selecting red from the palette.
Text alignment optionsIn the COMPOSE mode, you also have the choices of whether you want your text to be left-aligned (justified) , center-aligned , right-aligned and left and right aligned (both side justified) .
Numbered list and Bulleted listYou may also easily create numbered list or unnumbered list in the COMPOSE mode. For example, this list that I type here:
All I have to do is to highlight the list, like this:
then click the numbered list tool icon and the list will become a numbered list as shown below: