A few guidelines with respect to labbaik
(1) Make the labbaik by heart and recite this in abundance: specifically while ascending and descending the stairs while two groups meet at the mornings and evenings at the later part of the night after the prayers of all the five times.
(2) Whenever you start saying labbaik always repeat this for three times. (Bahar shariyat, Volume 1, Part 6, Page 1083).
(3) The Mu’tamar, i.e. the one who performs umrah and Mutamattea i.e. the one who combines umrah and haj on reaching inside of the haram when he touches the hajr e aswad (black stone) by kissing or just pointing the hands towards it and kissing them at that time he should stop reciting labbaik, instead start saying takbeer and tahleel ( greatness and praises of Allah) as has been said in the hadith:
أَنَّ النَّبِيَّ عليه السلام دَخَلَ الْمَسْجِدَ وَابْتَدَأَ بِالْحَجَرِ فَاسْتَقْبَلَهُ وَ كَبَّرَ وَ هَلَّلَ Translation: Nabi kareem sallallaahu alaihi wasallam entered the masjid haram and first of all he went  and kissed the hajr e aswad then engaged in reciting takbeer and tahleel (greatness and praise of Allah). (Nasabur raya, volume:3, Page 37)
(4) Mufarrid i.e.  would be over on pelting the stones to jamrathu al-aqbah (that is the eldest shaitaan) on 10 Dhu al-Hijja sharif.
(5) Gents would loudly say labbaik but not at a so high pitch to embarrass self or others.
(6) Whenever ladies say labbaik they should say this at a lower pitch. All gents and ladies are required to keep it in mind that apart from haj whenever one has to recite let it be at a low pitch as if he or she only could hear what they read. (Bahar shariyat, volume:1, part 6, page 1083) It is ok if due to a noisy atmosphere or deafness one could not hear what he recites, but the delivery of the pronunciation of words must be proper, which could have been heard, otherwise.
(7) Intention for ehram is the condition to the extent that if someone says labbaik without the intention of ehram then the stage of ehram is not fulfilled. likewise intention alone is not enough till such time that labbaik or in its place, subhanallah or Alhamdulillah or la ilaha illallaah (سُبْحٰنَ اللّٰہ , اَلْحَمْدُ لِلّٰہ , لَآ اِلٰہَ اِلَّااللّٰہُ) or any other dhikr of Allah the glorified is not added as has been the case of saying Allahu Akbar in the prayers, without which the prayers would not have begun.(Fatawa Alamgiri, volume:1, Page 222). 
(8) Saying labbaik with dialect one time is a must. If Subhanallah or Alhamdulillah, or la ilaha illallaah  (سُبْحٰنَ اللّٰہ , اَلْحَمْدُ لِلّٰہ , لَآ اِلٰہَ اِلَّااللّٰہُ)  or any other dhikr of Allah, the glorified is recited in its place with the intention of ehram the condition of ehram is fulfilled but saying labbaik is the sunnah.(Fatawa Alamgiri, Volume 1, Page 222)