There is a knack to using caulk, but it's a lot nicer to use and more forgiving than silicone! Cut the tip of the nozzle at an angle and size to suit the nature of the job- big hole for big gaps/ smaller hole for narrow gaps. Have a damp J cloth and a basin of water at the ready. Run the gun along the joint in a smooth continuous motion, applying gentle pressure on the trigger. If you need to stop, release the trigger and pull back the plunger just BEFORE you intend to stop. This will allow caulk build-up to exit where you want it and cuts down on mess and waste. In other words stop releasing the caulk BEFORE you actaully need to stop. I generally use a wet finger (my own!) to smooth the caulk, wiping off the excess with the wet J cloth as I progress along the joint. Don't overdo it on the wiping, the caulk will shrink slightly on drying. If you make a mess it's best to take it off with damp cloths and start again, but once mastered it's very easy to use and gives a superb finish to all paintwork and trim.