In order to distinguish prepositions from their adverbial sources, remember that just like in modern English, Old English prepositions have objects (nouns, pronouns).
Some Prepositions Most Commonly Encountered in OE
- butan/buton
- eac
- for, forþ, fram
- in, into
- mid
- of, ofer, on
- siþ
- to
- under
- wiþ
- ymb/ymbe
- æfter, ær, æt
- ðurh
- þurh
credit to following page:
https://en.wiktionary.org/wiki/Category:Old_English_prepositions