The point of greenhouse gardening is to have fun. Don't load yourself with more plants and projects than you can enjoy at least, try not to! I know well the hazards of greenhouse enthusiasms but I, too, try to limit my desire for an increasing variety of plants as well as a certain amount of yearly experimentation.
Also, don't let yourself be overwhelmed by the instructions here or in any other book or manual. Don't ignore altogether the "musts" and the "must-nots," but you don't have to be a slave to rules. Plants are tolerant of considerable variations in culture, provided you do not let them cook under the glass or get too parched for water.
In any case, there are no hard-and-fast rules for success. You will find that your plants grow best when you develop an affinity for them, and this comes from close observation of the plants plus a large application of common sense. Just take one step at a time. Master the fundamentals before you succumb to the excitement of special techniques or the challenge of difficult subjects.
Enjoy the following pages on what to do first and second year as a guide to getting started!