to practice using lugs, buy some 1"x.035" wall tubing and some 1 1/8 x .058 wall tubing. Cut the 1 1/8" into pieces, clean them up and braze them onto the 1" tube. If you are a rank beginner, you may want to cut some 1/4" or 1/2" pieces of the 1 1/8" and use those until the process clicks. You should be able to do this with 1" or 2" long sleeves before moving on. As always, everything should be clean and you should start with shiny or sandblasted metal. A degreaser followed by a die grinder or a Dremel with a 1/2" drum sander will clean things up sufficiently. You are looking to pull the braze material from one side of the small piece to the other. Only feed from one side of the sleeve. This is how lugs and crowns should be done anyway, so start doing it now. When you are done, soak the flux off and section the assembly to see if you got full penetration. Just pulling from one side to the other doesn't mean you got full penetration, you have to make sure to feed radially around the sleeve as well. You can feed from multiple points around the circumference to avoid using up all the flux in one area.