My personal "Rules Of Customizing" (in no particular order):
1) Always do something original. Do not jump on any bandwagons. In the Star Wars customizing community it has happened a few times, first was the Astromech craze of '95 and '96 in which nothing but custom R2 series droids were produced. The following year brought the beginning of a 4 year onslaught of Mandoloreans. For the last few years it's been Clones (although Mandos are beginning to make a comeback...). The biggest problem in limiting yourself to any one faction is that you will be constrained by the established aesthetics of that faction and not allowing for much growth as a creator or as a customizer. Also, the majority of the people doing these "fad customs" did nothing but their fad of choice and quickly burned out and left the hobby. If you are going to partake of any fad, be sure to still do more diverse work as well to avoid burnout.
2) Customize for your own enjoyment, do not worry about if anyone else will like it. As long as it makes you happy, go for it. Even though I love seeing feedback on my customs, ultimately I am doing them for myself.
3) NOTHING is too "rare" or "expensive" to be used as fodder. Anything and everything is fair game. I have used many a piece that has almost given collectors a coronary when they found out, but if it was something that I needed to use, it got used.
4) Look outside of regular toys for parts, some of the best parts are "found items". Parts form broken electronics, hardware bitz, you name it and I've used it.
5) Always keep learning and developing your personal customizing skills. I have been customizing since 1983 and I am still learning new techniques and tricks all of the time. Like any artform, it is a constant learning exercise.
6) Customizing is not a contest, there are no winners (unless you are actually in a customizing competition though
), just enjoy your hobby.
7) Do not be daunted by what others have done before you, even if the same character or concept has been done by someone else, put your own spin on it and really make it stand out.
8) Take your time and do not rush. I have seen alot of customs go south because they were rushed into completion
9) Do not "settle", work on the custom until you are actually happy with it.
10) Don't be afraid to "think big", no matter how ambitious a project looks, it can be done if you prepare and approach the project realistically.
11) Keep a good-sized "fodder bank". I have over 1000 3 3/4" figures (all different lines), several thousand accessories, and over 300 vehicles of all sizes and shapes (all amassed over the last 8 or 9 years) set aside just to be used in customs. Remember, the clearance aisle is your friend
12) Plan ahead. The pirate-based "Deep Sea Danger!" line I am currently working on was created and designed almost 2 years ago. As I work on them, I am planning out another large line for 2009 (the large line for 2008 was designed last year). My "Stargate"/"Star Wars" crossover from last fall was almost 10 years in the making (2 sequel lines were designed at the same time and are being prepped for next fall and fall 2009).
13) Every custom should have a "reason to exist" outside of just looking cool. I try to give just about everything I do a backstory. The only time I deviate from this is if I am making some random background Rebel pilots or troopers unless they play a larger part in my Universe. Sometimes the backstory takes on a life of it's own and actually makes me improve the figure's design as I am working on it (A'hks from "Through The 'Gate, Lies Adventure..." and Gurgles from "Deep Sea Danger!" come instantly to mind
).
14) Safety first! After accidentially severing the tip of my right middle finger last year while working on "Through The 'Gate, Lies Advenure...", I have redoubled my efforts to put my safety first and foremost while customizing. I still suffer the occasional X-acto cut (just got one Monday while carving out part of a "Deep Sea Danger!" droid that you will all get to see next week or the week after depending on how fast I recover from my surgeries), but not nearly as many, nor anywhere near as serious, as previous "accidents" have been.
15) This is probably the most important one- never limit your imagination! The imagination has an unlimited special effects budget, so go hog wild. I hate it when people tell me that there is no believable way Batman can exist in the Star Wars Universe, or that there is no way to link Stargate, the Lord Of The Rings, and G.I.Joe to Star Wars. No matter what Universe (or Universes) you work in, if you can imagine it, it can be done.