By this point you had better know what you want to do with your car. That being said, it's time to put the knowledge to work. You have an idea of what will be repaired and what will be replaced so get to it.

Body filler likes to stick to bare metal. It also likes to stick to sanded paint however that can cause problems. Ideally you would take all the panels down to bare metal, coat them with epoxy, then do your repairs on top of that. Now, we both know that everybody has an idea of how intensive they want this to become. So if you're going all out, get down to bare metal, coat the metal with a quality epoxy primer, and let that cure. I prefer PPG's DP90. The epoxy will create a moisture barrier that will permanently stop rust from occurring. Once the epoxy is cured FULLY, you can block sand over it with 180grit paper. This will accomplish two things. First, it will reveal low and high spots so that you can address the ones that you may not have seen. The second is that you have now provided mechanical adhesion for the body filler that will follow.

You will have to use your own judgment on fillers. I will tell you that you get what you pay for with body filler. If you cheap out you're only making it worse on yourself. You have three basic types of fillers:

1) There are reinforced fillers. These typically have short or long strand fiberglass mixed into them to strengthen the filler once it is cured. The short strand will be your best bet since it is easiest to work with. This type of filler is ideal for deep dents and creases. I'm not advocating this however; I will tell you from experience that this type of filler can fill 1/2" easily in one application. I wouldn't attempt more than that in one shot, but remember you can recoat it. I've found myself in situations that required me to do such things when I have had to fix cheapo used cars that no one wants to spend a lot on. The problem with these fillers is that they are hard to sand. I mean like concrete. Your best bet would be to start sanding as soon as it starts to feel somewhat firm and waxy on the surface. This is a small window of time so lay out your tools in advance. You can start with a surform file. This looks like a cheese grater. This will rough cut the shape for you without caking up sandpaper. Now that you have it roughed out, it's time to actually sand it. Kickoff with 40 grit on a block, board, or air file. You'll need to get it slightly lower than the surface level you wish to attain.

2) Standard fillers. These are the fillers that you have probably messed with a time or two. This is the category that good old Bondo gets lumped into. These will handle 3/8" in a single smear. You'll want to follow up a reinforced filler with this type. This will fill in all those pinholes that you had left. Same deal with sanding on these as was the case with the first type. My preference on this is Evercoat rage gold. You can finish sanding these with 80 grit followed by 180 grit, but you'd do better to move on to the next step.

3) Blending putty. These are generally polyester. You want to select one that is activated. The hardener will guarantee that it won't bleed through your finish and it will help to cover up all the nasty that you've just smoothed out. My preference here is Evercoat metal glaze. This is only good for 1/8" at most in one swipe. That's fine though since this is only icing the cake. This will also work for very minor spots such as door dings and very light hail dents. You can thingytail this with the standard filler for a smooth finishing filler that can handle a moderate spot. But it would still be good to follow up with the polyester anyway. Each smear will have grown in surface area slightly. This coat should go at least 2 inches further in every direction beyond the filler that you've already applied. This is what it is made for, hence BLENDING putty. This will enable you to transition your repair into the surrounding area. This will sand differently. For starters you want it to be completely dry before sanding. It will sand much easier. You don't want to start sanding with anything other than 80 grit and you'll want to finish it off with 180 grit.

Now your arms are dead and you are dragging like a sack of hammers. At this point if you're going for the gold you'll want to seal over the filler with another round of epoxy. This will encapsulate the filler and prevent rust migration. Again, let it cure fully. Most epoxies will need days for this to happen. Now you can block or board this sucker down with 180 grit and you're ready for a filler primer.

Filler primer comes in various degrees of solids content. This refers to how heavily the primer will build. You'll want to do at least 2 to 3 coats of primer. There will need to be a flash time of 10-15 minutes in between coats. You cannot skimp here or the end product will suffer for it. Filler primers need to be at least a 2 part product some will be 3 part (if they have a reducer in them). These products will be activated with a hardener or catalyst. This will give it a long life. DO NOT USE AEROSOL. Those primers are generally lacquer and they do not stand up well. You may notice that I have not mentioned etching primer. That is due to the fact that it is out dated. It cannot be applied over body filler and it is acid based which isn't exactly what you want your precious metal hosed down in. Besides that it does not offer a moisture barrier and is not effective unless it is applied directly over bare metal.

There are other things to be primed besides the filler. Look for anywhere you have chips, scratches, or anything that has broken the surface of the paint. You will have to feather edge these areas. Basically this means that you will have to sand through all the layers until you get down to the root of the damage. You will want each layer to have about 1/2" minimum between each of the rings where you have sanded through the finish. The greater the separation the better. If you've done it right you'll be able to place your hand flat on the surface and run it back and forth without feeling a harsh transition. These spots will need to be primed. Be warned that you may encounter an old repair (i.e. body filler) and that could make you more work, so sand carefully. Also every spot that you sand through is another potential spot for the primer to swell and leave a blowout ring or bullseye in the finish. I merely state this to make you think before you try to feather out 300 stone chips on a hood. If you have to you can get the primer to build up and fill in chips

Well that ought to get you into primer and you'll want it to sit in direct sunlight for a few days to preshrink the primer before you even think about sanding it. DO NOT LET IT SIT IN THE RAIN. Once it's all cured we'll pick up with the next section.