I have little investing knowledge or education, so I found that the following article lines up pretty well with my still developing thoughts on the subject and making the purchases through Sharebuilder. The article is especially helpful if you’re like me and have no idea how or where to buy stocks from, with the additionaly problem of having little cash to start with. Sharebuilder is a good, cheap starting point and he lists a few ETF’s to purchase starting out.
One thing to watch out for with Sharebuilder is the $4 cost per transaction. If you only have $20 a month to spend, I would recommend putting it into the Sharebuilder money market account or a different savings account and not making a purchase until you get to at least $100, thus reducing the fee as a percentage of your purchase. The site will let you do this automatically, so you could have it withdraw $20 a month to the money market account and then purchase an asset automatically once it has $100 to spend.
You can get a further primer on investing at Morningstar.com, where they discuss building a portfolio and different asset classes. You will have to sign up at their site, but the information is available to those at the free membership level. The Motley Fool is another resource to consider and their advice seems solid. Again, I can’t speak with authority, but I hope those provide you the starting point that they provided for me.