What do I need to know?

Hi! I'm new to all of this, but am very keen to learn as much as I can to start my own projects. I am looking at buying a reprap in the near future so I can start 3D printing and hopefully soon build my own 3D printer with bigger build dimension specs. What do I need to lean before I start building a reprap and then my own design? Anything from mechanics to software. Anything you can think of that would be good to learn and research before getting to far into this.

You need to learn... Patience...

If you have a love for tinkering, basic electronics knowledge, basic mechanical skills, know better than to touch things that burn/cut/electrocute you, and be willing to search/study/learn... then jump right in...

The most important thing you need to know is what you want to do with the machine and what sort of print quality is acceptable. Set goals and then pursue them, solving one problem at a time until you've solved all of them and the machine you end up with meets your goals. You'll learn everything else you need as you go.

Persistence!

I went down the same road, I knew I wanted a 3d printer, but knew very little about them. I started reading the WiKI, and the forums. looked at all of the designs, and took in as much information as I could before I even started thinking about what to build. I would say I spent 4 months just researching and reading. pay attention to other peoples failures, and the advice they get, this will help you not make their mistakes, and guide you to a better thought out machine. it was at least 6 months before I had a working bot, and several months after that before I made a print. Every failure I learned from and every success I celebrated.

Madmike8 said it best "Patience..."

Exploring further, look at other printers construction and at print quality with a critical eye. Try to understand the mechanisms and their limitations so you can correlate print quality with consturction/architecture. Delta's and Cartesian machines produce different types of flaws. Poorly made machines exhibit different types and degrees of flaws compared to well made machines. Learn from other's mistakes, and try to improve on their work. Don't be afraid to try different things and for god's sake, don't just follow someone else's BOM- use you mind!