I definitely recommend using the SlackBuild if there is one available for the program you want to compile. But, when one is not available, src2pkg can help you create a very compliant package and create a script for you in, its' own language, that will allow you to easily repeat the build later, if needed. It accepts many command-line options that deal with the most commonly needed options and of course saves these custom options for you in a very concise way. The esssential parts of a src2pkg script are just a few lines and are cleanly formatted so that any changes you make are easily visible. You can also use a src2pkg script with manually-coded lines that add any special commands not covered by it many operations, or comment out unneeded steps. This means that you can use the src2pkg script as a framework for building any kind of package you can think of.

As stated, there is no substitute for human knowledge or experience. src2pkg takes advantage of my own experience in compiling and building packages by including many operations which cover most common situations you might come across. It also can take advantage of others experience with the program, by using some configuration options from spec files or debian 'rules' files if they are included in the sources. It also can generate doinst.sh and slack-desc files for you and will automatically handle patches, desktop files, pixmaps and some conf files -simply by placing them alongside the sources. It can also be used to download the sources before compiling them.