Well, a portfolio needs to say everything you need it to say in as few of shots as possible. That being said, people will still ask for more, so if you have a port somewhere in the 10-30 image range, that's fine. ONLY your best though. If you have a super creative makeup session, and the model or subject has lines all over her face, don't show that image unless all of the lines are clean. Smell what I'm steppin' in? You should also look into a Print book (Book=portfolio) This you can take anywhere, and needs no instruction on how to use it! As far as a website, 500px has a nice layout, and lots of options, but you will eventually probably want to just host your own site. GoDaddy.com, or Host Gator are good places to start.
This (MM) could be a great place to build a portfolio, if you can find the people willing to work with you in the same direction that you want to go. If you want to do for example, Fashion, and everyone wants to hire you for Cosplay, that's not going to work well. Pick your shoots wisely, and make sure they benefit you in the manner you need.
Go here first. This is in the big black bar up above....
This is the place to tell people in your area that you are here, and ready to work. But, if you put in the ad that it's a "Paid Casting", this means YOU are willing to pay. Try to find Photographers and Models that might Trade with you.
http://www.modelmayhem.com/casting/new_ … litynotice
This is where you let everyone in your area know that you are here, and ready to work. Putting "Paid" here, means that this is your rates, or just shoot for Trade.
Going on a trip? Maybe a vacation? Wanna see if you can drum up a few bucks while your there? This is the place you let people in other cities/areas know your coming!
This is where you get your profile and portfolio on the front page! Let everyone on Mayhem know your out there. This is a good way to boost views/comments/lists. Usually, they like it if you return the favor!
Participate in the forums. This is another way to learn TONS of inside information you may not be able to get in a book. JUST READ THIS FIRST!
Or you may risk being eaten alive by rats that may lurk in the other forums!
Good luck to you! And.....Welcome to the MAYHEM!