Like a collegue from work but don't know how to tell her.

I work with a girl I like a lot. We see each other at work and that's practically all. We don't leave in the same town, we rarely work same shifts. so:
1. how to spend more time with her
2. how to tell her I like her (we are co workers but I don't know much about her private life as I know her for only about 3 months)
3. Is it better for me to wait awhile and to get to know her better and tell her I like her or tell her that right away?
4. if she rejects me, how will we be able to work together?
I have to say I'm a bit shy when dealing with girls :/

this is a tough issue since it is hard to get to know a girl when you barely see her. when working the same shift as her try to approach and start a conversation with her by using a "pivot" or friend that both of you mutually know, that works in the same area as her or is often with her. or you can ask a stupid question like "how do you work the fax machine?" or "The printers acting up can you help me out?" (even though you probably know how to work a fax or the printer is working perfectly fine it is only a means to start a conversation with her). If it were me I'd ask her to go out for a drink after her shift, or even better for her lunch break. for the more timid it may take you a while to get this step in but try to do this as soon as possible because you want to establish a uniqueness apart from an "employee of this company" meeting her outside of this environment will give her a different perspective on you.(not to be confused with asking her out, treat this as a normal friend or college get-together and she will feel the same way). if things go well make these get together with her a habit. And when you feel comfortable about your relationship with her ask her out.