Any crosplay tips or hints?

so i am a 13 year old boy who wants to crosplay as touko from pokemon black and white patricia martin from lucky star and miku hatsune i want to make it so no one will know about it so i cant go out and but stuff make up and other stuff i can get by stealing from my sister`s and i just want to know tips and hints and the most important thing how do i make it so i appear to have bigger breasts or so i do i don't care if it is permanent or not oh and i want to have a bigger chest no padded bras or stuff like that help i have about a month or so until the convention all non dumb comment are appreciated `sorry about spelling and grammar mistakes remember make the necessary items something that a 13 year old boy with 2 sisters can find around the house or things that are cheap and non obvious oh the purpose at a store so something that i can bye without anyone questing or knowing that i am cross dressing