"O Allah, I ask You for good through Your knowledge and I ask You for ability through Your power and I beg (Your favour) out of Your infinite bounty. Surely, You have power and I have none. You know everything and I know not. You are the Great Knower of all things. O Allah, if,in Your sublime knowledge, this matter is good for my Faith (Deen), for my livelihood and for the consequences of my affairs, then ordain it for me and make it easy for me and bless me therein. But if, in Your knowledge, this matter is bad for my Faith (Deen), for my livelihood and for the consequences of my affairs, then turn it away from me and turn me away there from and ordain for me the good wherever it be and cause me to be pleased therewith."
(Bukhari, Vol.1, Pg. 155)
Once an Istikhara is made, whatever happens will be in your favor. If you say yes to the proposal, it will be for the best. If marriage goes through, it will be Mubarak. If it does not go through, it will still be for the best, in sha ALLAH.
If you are Non-Muslim thn you should understand the true meaning of Prayer (Salat).
Estakhara does'nt mean dicovering of "GhAib" (unseen) things. Its seeking guidance in many ways.2) Usually, what are the signs / dreams that indicate the negative or positive outcome? Do you know some examples of dreams...?