Can someone explain to me an easy way to use who/whom in a sentence? I have read that it is not very important in grammar usage, but it still bothers me when I use it incorrectly.
The old rule was to use "whom" whenever "him" would be correct:
"Whom do you love?", because "You love him".
Modern English, especially modern spoken English, generally dispenses with "whom"; "Who do you love?" is much more colloquial.
In formal English it is still used after prepositions:
"They are the clients with whom we have had the the greatest conflicts and most serious difficulties." In this case you can't use "who".
However, the previous sentence is a bit contrived. Here's a more colloquial variation:
"They are the clients we have had the the most problems with."
For me, "whom" is only used either in very formal writing or after prepositions when displacing the preposition to the right would cause awkwardness.
Lou