What type of wood are you finishing? Also,what sheen finish are you using - high gloss or satin? If you want a really high gloss finish you should use high gloss varnish or lac. You should also use a paste grain filler after the sealer coat (do not use on maple or pine or other soft wood). I am going to assume you are applying 4-5 coats of finish, sanding between each coat with 220 gr. paper until you see no sheen of the last coat, in other words, smooth. After the final finish, sand with 200 gr then 600 gr. wet/dry paper (use water or ms as a lubricant). Then use 0000 steel wool and buff entire piece. Then you can take a power buffer (no need to use compound) and lightly buff piece. If you use polishing compound you will get a white residue in the pores that will not come out, Only option then is to stain again and then continue with finish. If you have used varnish it will take a little more elbow grease than with nc. As a professional finisher my process was an 18 step process, but you can get very good results witht the above.
Jim in Mayberry