If you want to avoid compatibility problems later when you edit your document, I recommend a radical approach. Note that Word only knows of paragraph styles and all the rest is direct formatting. This Word direct formatting must be interpreted and translated while loading or pasting. This will irremediably pollute the dictionary style of the Writer document, preventing you from fine-tuning it easily.
Consequently, I suggest the following procedure.
Start by thinking about which styles you need. Paragraph styles may be obvious (remember, though, that Default Style in Word should become Text Body in Writer).
You have words in italic, bold, … Define character styles for them. You can use Emphasis for italic and Strong Emphasis for bold. They are built-in. Modify if needed. For superscript and other “decorations”, create a custom style.
CAUTION! In Writer, you don’t create styles for their visual effects, you create them for the semantic value the highlighted sequence has for you. This means that several styles may end up with the same visual effect. E.g., emphasis and foreihn words are often rendered italic but they have not the same significance. Creta two styles, even if they are both italic. Later if you decide foreign words should be Roman+red, you change the “foreign” style and this will not impact the Emphasis words.
“Sections” in Word should be implemented as page styles in Writer. Warning! They are not managed the same, so you should learn the difference.
Paragraph numbering (list numbering) is not the same either. But if you’re a beginner in Writer, you can go with toolbar button direct formatting because list numbering with styles is one of the most difficult features for a newbie.
When you think you have listed all the styles you need, open a blank document and customise/create them. back up this document.
Copy now the original document paragraph per paragraph (or homgeneously formatted groups of paragraphs). Paste as unformatted text. This is very important to get rid of all “pollution” by Word. You lose your initial formatting but this is not really important. Apply the appropriate paragraph style and the needed paragraph styles on words which should be highlighted (Emphasis, subscript, …).
Backup at regular intervals.
When the whole document is imported, add the page breaks to switch between the various page styles. Note that part of them can be incorporated in paragraph styles (e.g. if a chapter must always start on a page with Chapter page style, configure this break in Heading 1 paragraph style).
Don’t be in a hurry. You’ll need several iterations to achieve your formatting goal. The procedure above guarantees consistency over the document without fossils of Word artifacts. A bit long but this pays off in the end.