tips for you...
Where to begin?
If you use an altoids tin, do yourself a favor and use a step drill bit to drill the holes, otherwise it is a MESS! the cool thing about the altoids tin is it is really easy to recess a tank in to it. The bad thing is that it is rounded and awkward to get a battery in there straight. I just finished a 3.7v bottom feeder altoid mod for a friend of a friend. It only took a couple hours.
Use 20 gauge wire. 18 gauge is way too thick to work with, and 22 doesn't handle enough amps. For me 20 is perfect. Lets see... don't skimp on your soldering iron and solder. Get the good stuff right off the bat. Don't throw your money away on the terrible Radio shack soldering irons and solder. I have some of their lead free solder and it's awful. Use flux... on everything. Get one of the bronze sponges to de-oxidize your tip.
Other than that, take your time, have fun, and post pics of what you make!
Where to begin?

Use 20 gauge wire. 18 gauge is way too thick to work with, and 22 doesn't handle enough amps. For me 20 is perfect. Lets see... don't skimp on your soldering iron and solder. Get the good stuff right off the bat. Don't throw your money away on the terrible Radio shack soldering irons and solder. I have some of their lead free solder and it's awful. Use flux... on everything. Get one of the bronze sponges to de-oxidize your tip.
Other than that, take your time, have fun, and post pics of what you make!