We just had a mojito Sunday here couple weeks ago and this is how we made them
Mint and lime in a jigger muddle then add ice pour rum (DonQ is what we used and it was really good at a very cheap price) and simple syrup. Pour into a glass and top off with Mist twist lemon lime soda. They were very good, not quite Casa Fuente but pretty darn close
Also for some they chose strawberry mojito which was same recipe except replace mint with strawberries and muddle.
I think the key is to make your own simple syrup as well, that stuff you can buy premade is junk.