Hello Fevdou,
How old are you?
Like others I would recommend searching for the Shettles method online; there is quite a lot of info out there on it/discussion groups too and although it is by no means scientifically proven there do seem to be some avid followers.
As well as the timing of intercourse, he recommends altering the ph level of your body through eating/avoiding certain foods. This creates a more alkaline or acidic condition in the cervix..boy swimmers dont like acidic conditions whilst girl swimmers favour alkaline.
I can understand where you are coming from in wanting a girl, I too thought about trying to influence gender as my OH and I would love a girl.. I think this desire is born out of our experience with children of both sexes in the family and how comfortable we feel raising each gender.
However, I have since aged and become more desperate mature, and so my viewpoint on this has changed somewhat. If you are going to be trying for a girl, you will have to time intercourse so that you abstain 2 days or so before ovulation, so that the short lived boy swimmers die before they can reach the egg, whilst the girl swimmers are still trooping on. Therefore conceiving can take longer as of course you are not having as much sex.. I will be trying when I am 30, and I do not personally wish to limit my chances and slow the process down by being 'picky' over what sex baby we conceive. Part of me thinks its even asking for trouble/bad luck, and that fate will decide the gender of our baby. Also, what if I did conceive a girl through intervening but she wasnt 'meant to be' and I had altered the course of what should have happened in my life.. does that mean I/she/we would be unlucky? Thats just the superstitious me!!!!
Also, I would quite like a surprise for my first one :)
Like you I think the most important thing is to have a healthy baby, and by no means would I be dissapointed with a boy (especially when you come on MN and realise that fertility problems are more rife than you expected, each child is even more of a blessing). I do think I would be dissapointed if all I had were boys.. rightly or wrongly.. and as I think we can only afford 2 children (3 would be a strain) I will think again about trying to influence the gender of the baby for my SECOND bugs, not my first.
Just another perspective!
I will post again with some tips. Good luck!