I just painted my vinyl coated, steel front door. I followed the directions to the “t” that I found on reputable sites on the web (washed, sanded, primed, used latex paint). The first coat looks extremely streaky. I used a polyester brush. So, for the second coat, should I do something different?
You followed what directions? Apparently you did not get the best advice… you really didn't need to wash or sand… unless it was EXTREMELY dirty (in which case only washing would be needed), and you didn't need to prime either… unless it was bare steel… and what brand of topcoat paint did you use? Most are subpar… and how did you apply the paint?
So my advice now is to Prime the whole door using a Pigmented Shellac Sealer Primer (use brush and roller), then topcoat (1 coat) with Sherwin Williams A-100 (semi or satin)… and brush it in only around the edges, door knob, or window (if there is one)… then roll it using a 3/8 in nap roller cover… and after it sets up (about 10 min) roll over it again, using a "dry roller" (the roller you used, but don't add any more paint to it from the tray)… this will tighten up the stipple to give it a nice uniform finish… Good Luck!