Remember that people will be RPing on this ship. Don't design a ship that you think would be neat for people to look at. Don't design a ship that would be great against the Jem'Hadar. Don't design a Borg killer. Design a ship where STF members can Role Play. That means even a specialty ship -- one that focuses on warfare, science, medical, etc. -- should be well rounded. It should also have enough weaknesses that it won't be able to destroy the entire Dominion Fleet. While it may be tempting to design one of these superships, and even if you think it could be done, that doesn't make it a good ship in the STF context.

Don't reinvent the wheel. If it travels at warp, let it use a warp core. You don't need to recreate FTL drive, because you can't. Warp drive is not possible with our current understanding of the Universe, and the nature of the Star Trek Universe is not clear enough to determine how warp drive works now, much less replace it with something bigger and better. The same holds true for phasers, shields, warp cores, and other main technologies. And don't be ashamed to borrow ideas from other ship designs in STF. Building on the backs of giants is an established practice in science and in STF. Just make sure you give explicit credit to the initial design and designer. Otherwise it's plagiarism, and don't expect a ship to pass then.

Be creative. If the last paragraph seemed to suggest that you shouldn't be creative at all, then you missed the point. New technology isn't bad. It can be fun and constructive, and make for some really nice RPGs. But you need to make sure that your new technologies are very well described, and that they work. For instance, if you are designing a new weapon, then make sure that the way it works makes sense in terms of the Star Trek context. It has been established in numerous episodes that lasers are of almost laughable impact on Starfleet ships. That's why everyone uses phasers and disrupters. So don't try and make lasers bigger and better, try and make phasers bigger and better. Or try to invent a replacement for the phaser. But if you are planning to invent a new technology, be forewarned: Expect a lot of setbacks. It is not uncommon for a new technology to simply not be up to snuf, and therefore not be passed in any form. You should not take it as an attack against you, but a statement that the technology is unfounded, unnecessary, or unworkable.

Don't overdo it. There are a series of recommendations that the ED often makes repeatedly, so I will collect them here so that they need only be said once, thus saving bandwidth and server space. The most important of these is speed. It is very tempting to make a ship faster than the last on, and then even faster than that. Unfortunately, physical constraints and playability make this a bad idea. Impulse speeds, for instance, are measured in terms of a fraction of the speed of light. The Galaxy-class Enterprise-D, for instance, had a maximum cruising speed of .25c, that is, one quarter the speed of light. Theoretically, it could push itself up to .92c, but doing so did nasty things to the structure of the ship and caused all sorts of time dilation relativity problems. In fact, those relativity concerns kick in, realistically, around .4c. For that reason, the STF Engineering department has officially stated that ships are restricted to under .35c impulse speeds in their fundamental design, and well below .35c is strongly encouraged. Lest this seem too unreasonable a suggestion, keep in mind that even at .27c a ship could easily outrun the Enterprise-D, and that the GMD has also made it clear that enemy ships must follow the same restrictions. Warp is not quite as stringent, but there energy and playability concerns come into play. Remember that warp is measured on a logarithmic scale. Warp 9 isn't 9 times the speed of light, it's 1516 times the speed of light. That's pretty darn fast. Also, as the warp speed increases the energy requirements increase, to the point that warp 10 is both infinite velocity and and infinite energy requirements, just as under Einsteinian physics the speed of light requires infinite energy. And when speed increases much farther than warp 9, the power usage increases faster than the speed, so warp 9.4 is actually far less efficient than warp 9.1. In terms of playability, the speed should also not be too fast, as it makes for nonsense RPGs. In fact, in many cases a slower ship can be better than a fast one when it comes to Role Playing. In practice, a maximum warp speed of 9.8 should be sufficient for both physical constraints and RPG usage, as well as satisfy the innate desire to say "Mine is faster than yours." Yes, some ships seen in the show have a higher max warp speed, but in order to make RPGs more challenging this is the STF limit. Most ships, however, can make do with far less than that and still be great designs, depending on their purpose. Staying far under these caps will increase the chances of a ship being approved.

Use standard notation. That means that you should always use the SI system of measurement, more commonly known as metric. Mass is measured in kilograms, distance in meters, and time in seconds, in all cases. When referring to super-high speeds, use a fraction of c, the speed of light. Avoid the complicated and unwieldy Imperial system (also known as English, also known as American, also known as that-damn-system-with-feet-and-pounds) like the Bolian Plague.