Darryl
In addition to the answers you have gotten above - you will hear the term b2b or bushing to bushing. That term is used to denote making the whole pen 'straight' and as thin as possible for the hardware.
You can do this, and for a few kits, many people thing it works great. But for most hardware, the general consensus is that some curvature looks best. Slimlines are a great set of hardware because the amount of freedom you have to try things out are infinite.
Welcome to the vortex... Make sure you save that first pen, no matter how it turns out - to remind you of the fun of the beginning!