Its quite simple, all you have to do is: Start W, then f*ck these minions until lvl 2, take e and go hard for these level 1-2 enemies. After that you should just keep it up and do it over and over.

If you are playing with a bro then remember to communicate with him and make him last hit the minions with your w passive on and its gonna be the fastest lvl 2 of your life. when you are ready to all in then just get as many spears in your opponent as possible.

Nami, Nami, Nami... Well first of all she got a heal that is good for poke and heal Ofc. Next she has a bubble that gives kalista time to fire these spears in her enemies. Also Kalistas passive works really well with Namis e and overall just namis kit. Namis ult is ok i guess u can do a double knock up by using kalistas ult and then Nami uses her ult.