May one do the bedikah on a night prior to the night of the 14th?
If one wants he may do the bedikah with a candle on all of his rooms on any night prior to the night of the 14th, although a blessing is not said, and he must make sure not to enter any more Chametz into those rooms that he checked. For this reason [that no blessing is said when checked prior to the 14th] it is proper to leave out at least one room from being checked in order for one to be able to check it on the night of the 14th with a blessing and thus not forfeit the blessing with his own hands [by having checked it all prior].
Preparing ones house for the bedikah:
All rooms which need to be checked need to be swept prior to the bedikah. Every person should warn his family to also sweep under the beds as perhaps some Chametz has rolled under it.
The reason for sweeping is because without sweeping there remains much dust [on the floor], and one is thus not able to check well.
Checking ones house after the sweeping: After one has swept well in all places, he has to return and check all the places with a candle, in the holes and cracks which require checking. Even under the beds one needs to check with a candle after the sweeping, unless there are chickens found there, in which case we assume that they ate all the Chametz that has rolled under the bed.
However under the benches [in the dining room and kitchen] one needs to check with candles even if there are chickens found there, as if it is a room which one eats in it is impossible that Chametz has not fallen there, and there is thus for certain Chametz under the benches, and the doubt of whether chickens ate it does not remove the certainty of the Chametz which is there.
The reason for requiring checking even after sweeping is because perhaps there is some Chametz there, being that the sweeping does not help at all for whatever is inside the holes and cracks.
Must one check with a candle all the cleaned areas?
One must check with a candle all areas which have not been previously checked at night with a candle [or flashlight and the like], even if he has completely cleaned and checked that area by day. However some Poskim rule that once the area has been cleaned it no longer needs to be checked at all. Othersrule that all moveable items merely require a swift glance at night, and not a thorough checking.
 The reason for this is because: the search which is being done now is not the main time for the search to be done as was instituted by the sages. As they instituted it to be done on the night of the 14th. [436/1] This ruling is similar to the ruling there in 436 that no blessing is said when one must check before the 14th.
 Seemingly this is going in accordance to the opinion which holds that one does not have to recheck. However according to those which hold that one does, he does not forfeit the blessing even if he checks it all before hand. Alternatively, this is going according to the final ruling that one does not say the blessing when he checked it all previously, due to safek brachos lihakel.
 433/42 See Q&A for a thorough discussion of the meaning that is implied from this Halacha and its reasoning behind it.
 So rules Michaber 433/11; Magen Avraham 433/20; Admur 433/39 that sweeping does not suffice and 433/6 that checking by day does not suffice; Mishneh Berura 433/45 [however in Shaareiy Tziyon 432/12 he rules differently]; Rav Fuchs in Sefer Hakashrus; Nitei Gavrial 135; 136; 161, brought also in Piskeiy Teshuvos 433/8
 Piskeiy Teshuva 432/2; Eimek Halacha 143; Chachmas Shlomo 433, if checked three days before hand no need to recheck. Shaareiy Tziyon 432/12; Shaareiy Teshuva 433
 Daas Torah 433