If you’re serious about becoming a freelancer you need to have a completely separate site/social media account specifically for that. Make it professional and only use your work on those sites. Having a personal account attached to that kind of stuff would only make you look like someone who isn’t taking it seriously.
Regarding asking for payment for the requested model, yes you should. This could be you entry into freelancing. You’ll more than likely not get the price right, but find what you feel is suitable for your work and offer it. If they say no then move on. Don’t start providing free work of this kind. It will only make it harder to find paying work.
Freelancing is a business all on it’s own, except you’re the business. By building a reputation online through a solid portfolio that people can see you’ll start to attract people. You get out of it what you put into it.
