You have to let things gas off and harden up like Ty mentioned, if this is all dope. We are talking a few weeks sometimes depending on how heavy the dope is put on and weather conditions and such. After a few weeks, pick a spot on the bottom of the model to practice on. before you can make something shiny, you have to flatten it and make dull. Block sand the clean lightly with some 800 wet or dry at first and work your way to 1200. Sometimes it pays to go to 1800 and 2000 grit. . Do all the sanding wet with water and a few drops if dish washing detergent in it to help the sandpaper cut the paint and wash away the waste. Work lightly and carefully. The are should be nice and dull evenly all over the area when you are finished. Then talk some of your polish and try it on that area to buff it out and bring in the shine. There is a significant amount of elbow grease involved here and it won't happen in a few minutes. All the sanding and rubbing takes some care and it takes some time to get the feel of how much pressure it takes while sanding and buffing. If you are close to being correct on procedure, the shine will start coming through. Sometimes it takes some rubbing compound to knock off the top before polish works there are many new materials and compounds available at the auto paint supply stores. Take you model in to show them what you are doing and they can recommend the proper materials. There is no doing this part fast. Some guys work on rubbing the model out a little at a time as they do the initial test flights and such to make good use of the time. You may not see it while you are doing it, but significant weight can come off the model during the sanding and biffing process. Just keep at it, that is the only way to learn.
Type at you later,
Dan McEntee
There have been MANY threads on this process in the 20 years the forum has been around, look them up. Also, spend some time watching the Windy videos on the subject. He explains very well what you need to do and why. Even if you are using more modern finished, the process is basically the same.