You've got to have fabrication skills, that's for sure. In fact welding is the least important skill when it comes to metal working. Here's my list of most important skills.
1. Planning. Take the time to visualize your creation. Think about size and function and appearance... Then draw it out with the measurements and cut list. If you don't? You'll end up with a big mess.
2. Safety First. You don't want to lose an eye or a finger. Put on your protective gear. Duh!
3. Tack everything. Don't weld a single thing until it's all together. Sure as heck, you will find a glitch somewhere, and you'll need to fix it.
4. Make it nice. You are not a 2 bit chump off the street..(are you????) YOU ARE A TALENTED CRAFTSMAN NOW. so cut that ugly, doesn't-look-right part off of there and do it perfect. Use a square and measure corner to corner.
5. Finish it. take this last step to put some WOW into it! Don't just paint it... Powder Coat it... don't just clean it.. polish that thing.