1) Suggested secret size is 600x450 pixels. Maximum size is 600x600 pixels.
2) Comments are screened, but please submit secrets anonymously.
3) Host your images as tinypic.com or imgur.com, preferably. If it goes against their TOS you can host it elsewhere. Please provide the URL to the actual picture, nothing else. You don't need to code it (and LJ doesn't use BB/forum code, so stop it). Just paste the "Direct link for layouts" into the comment box.
4) WCIF and help requests won't be posted. You can ask your questions anonymously at sims_101.
5) Further rules/recommendation are listed on the community info page.