Summarize:

If you've never made brake lines before, you'll need to do some research to ensure you're installing the correct parts. Look in the owners manual, or bring the old brakes lines off your car and into an automobile shop. Head to the local auto shop and grab the parts necessary for your overhaul. You should be using the old parts as a guideline for the lengths and sizes, as all cars will have slightly different specifications.  Don't forget to purchase the appropriate brake fluid as well. You'll need to fill it later. Again, when in doubt, do some research. The internet is filled with specific advice for each make, model, and even year of the car. As long as you have the right sizes and fittings, you can buy brake lines that are already double flared. Make sure, however, that the pre-flared line will fit your car by comparing to the old lines. These devices are relatively inexpensive, and will quickly pay for themselves if you're flaring multiple lines. They come in three basic varieties:   Manual: The cheapest, most basic option (usually under $100), these are perfect for most non-professional mechanics and hobbyists. Can even be borrowed or rented from many auto stores.  Leverage Manual: Like manual, but require less time and force for each flair. If you restore vehicles frequently or want a complete overhaul of your lines, this may be worth the extra money. Usually several hundred dollars.  Hydraulic: Makes quick, even flares, but is likely overkill unless your making multiple flare lines a day or need to save time (like an auto-mechanic might). Can get very expensive. You need to make clean, quick cuts in the brake tubing or else your lines will be weak and prone to leaks. Tubing cutters clamp to the tube and then rotate around the tube with a small knife, slowly cutting in a circular motion instead of pushing down to cut, which could pinch the tubing. They are usually less than $30. In a pinch, you can use a hacksaw. If so, however, use only light pressure, focusing on cutting side-to-side instead of up and down.
Research the appropriate brake line fluid, fittings, and sizes for your vehicle in either the owner's manual or at a local auto shop. Purchase a new set of brake tubes, fittings, and flare nuts with rust-resistant alloy finish. Know that you can purchase pre-fabricated lines at most auto stores to save time and energy. Purchase or rent a double flaring tool kit. Purchase or borrow a tubing cutter.