Whats the best fertilizer to create a extremely thick green lawn to apply right now in spring ?

i want to get my lawn that's just waking up from the harsh winter nice and thick and green to get a good full lawn this year and help keep out those dandy lions, dead patches and prickly weeds. there's no weeds right now but there are a lot of yellow mixed with green spots. so there's a good sale for a turf builder and a weed and feed which one should i use to get a think green lawn right now in the spring ?