Auto body repair & detailing: block sanding, grit paper, filler primer

Question
ok  i want to know how to block sand the right way. I try and i still get waves or high spots. the grit of paper. i primier and i can see the bondo.and also i have rust on top and trunk of car did not go threw so whats the best way to fix this. thank you  

Answer
count on the size of the aera your sanding and the contor of it. if its a big flat area you want to use a long sanding board  if it a small aera use a short board if it a bodyline or hard contor aera use a sponge block. the second part is to not sand in one direction sand back and forth than up and down. untill you can take your hand flat and feel the area smooth no high or low spots on it. use 180 grit paper to do it . oonce you get a nice smooth feel. finish it off with a 6in da sander with 320 paper to get rid of the sanding lines. prime it with filler primer it will fill in all pinholes and minor scratchs  wet sand that with 1500 paper than paint away. as far as the rust gos use the same as above. it will work . remember it is a time thing to get it right.. don.t rush it will look better . and believe me you will get big arm musles lol.. good luck