Gimmicks That Should Be Avoided
Some types of gimmicks are prohibited or strongly discouraged in the TRC Gimmick Rallye Rules. Others just create problems that are best avoided.
Special Instructions (SIs)
Provide for Special Instructions (SIs) and other emergency instructions and signs. There must never be any gimmicks based on Special Instructions. Doing so would make it harder for other rallyemasters to provide directions that must taken at face value.
SI Side Effects
Sometimes an SI will have a side effect. For example, an SI on the RI page might bring a Note into effect. Or it might precede the Note, but a Note may be brought into effect by the preceding RI and not by the SI. All these situations confuse some beginners, who don't understand the limits of a promise of "no gimmicks on SIs." Consider using a non-SI instruction (perhaps a Traverse?) rather than an SI as the non-RI instruction that triggers side effects. Or consider stating explicitly (in the SI part of the Order of Precedence) that an SI can have side effects (but don't expect that phrase to be sufficient without definition or explanation). Your explanation could say, for example, that an SI might DRI 13 or CRI 14. After that, the SI is completed, and if RI 14 is faulty, that is not a gimmick on the SI.
To avoid difficulties publishing the results, it is strongly recommended that you do not include gimmicks on: car number, driver & navigator name, or email addresses.
Delete Gimmick (DG)
Older rallyes sometimes used a DG (Delete Gimmick which caused you to find this coursemarker) instruction to undo a gimmick, after rallyists had caught the gimmick and recorded the resulting coursemarker. Rallyemasters that use DG assume that rallyists understand what gimmicks they want to delete, and what the result of deleting the gimmick will be. This was particularly frustrating when there was a "DG" in both the full and partial credit coursemarkers of a combination gimmick. Was the gimmick being deleted by the full credit CM the one that separated it from the partial or the one it had in common with the partial? Who knows? You usually needed to know the rallyemaster.
Rallyists (especially less experienced rallyists) can easily end up deleting the "wrong" gimmick, and may do the wrong thing in response to deleting the right gimmick.
Alternatives to Delete Gimmick
One alternative to using a DG instruction is to send rallyists who catch the gimmick into a CP. By asking rallyists which RI they are working on, the CP workers can determine whether rallyists are entering the CP normally, or whether they are entering the CP early/late because they caught a gimmick.
Sometimes Delete Sign (DS) can be used instead of DG. Rallyists aren't perfect at knowing if a street sign or a (perhaps bad) coursemarker should be deleted, so don't be ambiguous when using DS. Definitions must make it clear if that one surface is being deleted or all signs with identical wording.
Another alternative to using a DG instruction is to set up the gimmick with a "monster" style instruction that is in effect only for a short time.
You could also have rallyists call the RM (perhaps on a different number than "I'm confused" calls). The RM can ask what CM they are at (to confirm they reached it), and explicitly tell the rallyist which phrase or sentence to delete (or alter) in the GIs.
Straight as Possible (SAP) Gimmicks
You may create gimmicks based on the Straight as Possible rule. The most common is a spot where the main road (and center line) curves, but a side road branches out straight ahead. Moffett Park Dr and Moffett Park Ct is such a spot.
Do Not Make Ambiguous SAP Gimmicks
However, there are places where you should not attempt a SAP gimmick. It may be obviously SAP to you (or on a map), but these are not generally agreed as SAP. If a side road comes off a curve, the side road might be SAP during the approach, or it might be SAP where the street-naming sign is, or at the spot where one would need to choose whether to turn onto the spur, but not at more than one of these points. This leads to confusion and protests.
This is a partial list of places where you should not attempt a SAP gimmick and add to this list when you find additional ones: