It's worth mentioning up front, that this is general advice; it can be (and should be) foregone in cases where it would be beneficial to do so. People can reasonably have differences of opinion.
There's analogous question title advice on various sites throughout the StackExchange network, and I'll cite these throughout.
General advice
Ordinarily, the title should be the question.(meta.SE, meta.SE, meta.physics.SE, meta.drupal.SE) It's more formal and professional, and helps to restrict the answers and comments to those directly related to the question.
However, it can be beneficial to do otherwise: "...the title should communicate the question itself as faithfully as possible"(meta.math.SE) but "...don't insist that your title be expressed as a perfectly formed English sentence"(meta.SE).
The specificity of the title should match the specificity of the question.
If a question title asks a general question but the question content asks a specific question, subsequent questions which seek to ask the general question might be incorrectly closed as a duplicate. It can also give rise to the problem: "The title was exactly what I was looking for, but the question itself had nothing to do with my problem."(meta.SE)
If a question title asks a specific question but the question content asks a general question, users might ask the general question not realizing there is a duplicate.
Avoid ambiguous titles.(meta.SE, meta.Judaism.SE) As in the example in the question.
Concerning title length...
Everything should be made as simple as possible, but no simpler. -- Albert Einstein
Basically, "keep it short"(meta.SE, meta.SE, meta.stats.SE) but "don't be afraid to make the title long"(math.SE, meta.drupal.SE).
Make titles useful for searching by including words that people will search for(meta.SE, meta.stats.SE).
Avoid reusing tags in titles(physics.meta.SE, meta.SE) except when they make the title read better(meta.SE):
To be clear, I think it is fine to duplicate the tags in the title, but only when they can be worked into the titles organically and conversationally. -- Jeff Atwood
Avoid words like "problem", "question"(chemistry.meta.SE), "doubt"(chemistry.meta.SE), "help", "please", and "advice" in the title(meta.SE). Also avoid "Could anyone..." or "Could someone...".
Sentence case is easier to read in titles(meta.SE).
Islam.SE specific advice
Avoid the word "Islam" in titles as every question is about Islam, unless it makes the title more readable.
If you're after a specific viewpoint (Hanafi, Sufi, etc.), it should be worked into the title. This is important for efficiently identifying (non-)duplicates.
What is the Shi'a ruling on such-and-such? -- goldPseudo
might be a different question to "What is the Sunni ruling on such-and-such?", so it's best that they are not both titled "What is the ruling on such-and-such?".
Don't use "(saw)", "(pbuh)", etc. in titles. There's a specific meta.Islam.SE post: http://meta.islam.stackexchange.com/q/1131/
Prefer English over Arabic transliteration in titles. This is an English-language site, so the default should be English (although this should be balanced with searchability).
When Arabic is necessary, descriptors help. A title like "What's in Riyad As-Saliheen?" is equivalent to "What's in [something]?". From the title, we learn that "Riyad As-Saliheen" is an object that things can be in, and the author wants to know what's inside it. (I changed it to Where do the ahadith in Riyad As-Saliheen come from, and what grade are they? to match the wording in the question.)
Beware that "Qur'an X:Y" is not uniquely defined as some authors include "Bismillah al-rahman al-rahim" in their numbering while others don't.
Other
Ensure the question in the title is consistent with the question in the post.
Try to find an answer to your question by copy/pasting the title into a search engine (before posting the question).
Critical information should not be contained solely in the title.(meta.chess.SE)
Starting questions with "How to...", "How do I...", and "What is a..." is debated.(meta.SE, meta.diy.SE) At Islam.SE, we probably also have problems concerning "Is it permissible to...", "Is it okay to...", "Is it acceptable to...". I'd suggest go with whatever seems best for a particular question.
