This is a check list for ABRSM Singing Grades 1 to 5, and for general aural tests in Grades 6 to 8 (tests 6b, 7b and 8b). I find that many students are in need of a systematic approach to the subject, which I aim to provide through this checklist.
Metre
Look at the time signature:
Is it the crotchet (quarter note), the quaver (eighth note) or the minim (half note) that is one beat long?
What are you going to count? (This is NOT the same question as "How many beats are in the bar?")
Rhythm
Read the words in the rhythm of the music (if the test is wordless, sing it to 'da')
Clap the rhythm, especially dotted rhythms

(This image is part of my pamphlet “Theory for Singers”)
Pitch
Work out the key note and play it on the piano
Ask yourself : Is the piece mainly scale or arpeggio
Sing a scale or arpeggio in the key of the piece:
doh-mi-soh-mi-doh
or
doh-re-mi-fah-soh-fah-mi-re-doh
Practice the first bar
FInd out where in the accompaniment you get the first note from
Pitch the tonic and the first note
On which beat of the bar do you start?
Resources
There are some books I recommend, and use frequently, but none of them is a substitute for a teacher.
Successful Sight Singing by Nancy Telfer (Kjos 1992). This is the only book I have come across that begins with a fifth (rather than a second) as the first interval to learn and memorise.
Learn to Read Music by Howard Shanet (Faber and Faber 1957). Transcription of public lectures of a remarkable attempt to teach adult beginners how to read music. Creative and imaginative approach that is also thorough and rigourous. Needs access to a keyboard in its later stages.
Sight Sing Well by Jonathan Rathbone (Edition Peters). Far and away this is the best Sight-Singing book for younger students. It is a proper course, not a quick fix, like my checklist above.