My recommeded process {others may choose a different route}
1) Paint the PE on the fret. Paint the PE the predominant camouflage color. You will hand touch up nicks & cracks in the paint later. You will also hand paint camouflage color differences after installation.
2) Measure your railing runs between logical end points: bulkheads, previous rail runs, ladder ways, gun tubs, etc. Measure shorter runs (2 - 3 inches/5 - 7 cm Max). Resist the urge to do an entire side with one piece of rail, just because you have one. That is a sure recipe for wavy rails. Use a draftsmans dividers to measure your cuts.
3) Measure twice, cut once. Use a new #10 Xacto blade (the rounded one) on a piece of glass or bathroom tile. Cut with a rocking motion, like a paper trimmer. Use a fine sanding stick to polish down any nubbins remaining where cut.
4) Make bends as necessary. A tool like a Hold-n-Fold or Etchmate is helpful but not necessary. Use some square-nose pliers or fold on a hard surface between a pair of opposed razor blades. Rounds can be bent using some drill bit shanks (go one or two sizes smaller to allow for spring back).
5) Use some white glue to tack the part in place. My favorite is Aleene's Tacky Glue from the craft store. The white glue grabs, yet allows time to reposition the part. Place a pin-point size dot of white glue at each end of the run and every 1/2" (1 cm) of the length. Mistakes can be cleaned up with water.
6) When the white glue dries, go back with some CA and run a fine bead along the bottom rail.
7) Work top to bottom and inside to out. This minimizes the chances of disturbing previously installed parts.
8) Hand paint nicks & cracks in the paint.
9) A final coat of flat will hide the shine of the CA and will help to blend everything together.