For most cosplay a smile sewing machine is fine, nothing too major you basically needs to look into a few things when buying your first sewing machine. Things like the type of patterns it can do with a needle. You want ones that do regular stitches but ones that can also do stretch stitches or zig/zag patterns, these setting are for spandex and stretch materials.
Cosplays planned for AN/13, FE/13
Jeanne - Bayonetta
Samara - Mass Effect 2
Sheik - Legend of Zelda