A way to get a good fit when installing decorative molding is to install the first piece with a square end. Then cut the second piece at a 45-degree angle in a miter box or saw to expose the profile. Use a coping saw and follow the edge of the profile, under-cutting it about 3 degrees. This lets you get a good fit, even if the corner is not perfectly square.
If you will be working in close quarters attaching new molding to walls or ceilings with finishing nails, first check out your hammer handle. Inevitably the handle end will hit the adjacent surface in spots. Either use a new hammer, clean up the handle of an older hammer, or mask the end of the handle with masking tape, especially if the handle has an older covering of black rubberized material. Doing this before you start can save you time that otherwise would be spent cleaning up or repainting over the scuff marks.
To save trim during remodeling, use two small, flat prybars. Slide the thin end of one behind the trim, pull, then insert the second in the space that opens up. Alternate pulling each bar to inch the trim off. If finishing nails protrude from the back, use slip-jaw pliers with a rounded top jaw to pull them through.
If you are frustrated with the choices of molding styles at the lumberyard, make your own. A 15-piece molding head set for radial or tablesaws costing less than $60 can provide endless options. If the stock cutters don't meet your needs, you can easily re-grind a new profile. Hone the edge and within minutes you can produce customized molding for new projects or to match molding no longer available.
To store dowels, molding and the like neatly off the floor in your shop, you can use empty 3-lb. coffee cans. Attach one can with a bottom 6 in. off the floor. Then attach another with both ends cut out about 2 ft. above it. Slide material down through it into the bottom can.