It is most of the time
the best answer you could give
and the worst you could get
Istikhara is used to ask Allah to help you decide between two things.
Ibn Abi Jamrah said: ‘With regard to matters that are waajib (obligatory) or mustahabb (liked or encouraged), there is no need for istikhaarah to decide whether to do them, and with regard to matters that are haraam (forbidden) or makrooh (disliked), there is no need for istikhaarah to decide whether to avoid them. The issue of istikhaarah is confined to matters that aremubaah (allowed), or in mustahabb matters when there is a decision to be made as to which one should be given priority.’
The prophet pbuh said: ‘If any one of you is concerned about a decision he has to make, then let him pray two rak’ahs of non-obligatory prayer, then say:
Allaahumma inni astakheeruka bi ‘ilmika wa astaqdiruka bi qudratika wa as’aluka min fadlika, fa innaka taqdiru wa laa aqdir, wa ta’lamu wa laa a’lam, wa anta ‘allaam al-ghuyoob. Allaahumma fa in kunta ta’lamu haadha’l-amra (then the matter should be mentioned by name) khayran li fi ‘aajil amri wa aajilihi (or: fi deeni wa ma’aashi wa ‘aaqibati amri) faqdurhu li wa yassirhu li thumma baarik li fihi. Allaahumma wa in kunta ta’lamu annahu sharrun li fi deeni wa ma’aashi wa ‘aaqibati amri (or: fi ‘aajili amri wa aajilihi) fasrifni ‘anhu [wasrafhu ‘anni] waqdur li al-khayr haythu kaana thumma radini bihi
(O Allaah, I seek Your guidance [in making a choice] by virtue of Your knowledge, and I seek ability by virtue of Your power, and I ask You of Your great bounty. You have power, I have none. And You know, I know not. You are the Knower of hidden things. O Allaah, if in Your knowledge, this matter (then it should be mentioned by name) is good for me both in this world and in the Hereafter (or: in my religion, my livelihood and my affairs), then ordain it for me, make it easy for me, and bless it for me. And if in Your knowledge it is bad for me and for my religion, my livelihood and my affairs (or: for me both in this world and the next), then turn me away from it, [and turn it away from me], and ordain for me the good wherever it may be and make me pleased with it.”
(Reported by al-Bukhaari, 6841; similar reports are also recorded by al-Tirmidhi, al-Nisaa’i, Abu Dawood, Ibn Maajah and Ahmad).
The two rukahs prayed can be any sunnah (naafil prayer). If a woman is on her period and cannot pray, she can do the istikhara duaa without praying.
One thing I want to point out is that istikhara doesn’t always come in the form of a dream. You won’t necessarily get a dream to guide you, you may also get just a really good/ bad feeling about something. Go with your gut instincts on what you think is better, and if its not Allah will send some sort of obstacle to stop it or some sort of encouragement to choose the other option (like for example one becomes easier to achieve, etc)