It depends how you invest.Thanks. I wish I knew how to invest. I'm scared of hidden fees.
If you invest through a broker, make they do a brokerage account, and get their commission in writing. generally any legit broker will only take a small (3%) percentage of your annual growth, and get nothing if you lose money. The only fees you need to know about investing is whenever you MAKE money (as in goes into your checking/savings account) you need to pay capital gains taxes (typically 0%, 15%, or 20% on the earnings, this depends on your taxable income for the year). There are exceptions, for example, if you trade rapidly, say buy stock X today then sell it tomorrow your capital gains tax on the profit becomes == to your annual tax rate. So the motivation is to keep everything you buy for atleast a year before moving off the position. Now there is NO tax on a loss, in fact you typically can write off losses as a tax deduction for the year. However if you're investing you don't want to think about losses.
Remember, with all investing, it's only worth what you sell it for. Which is exactly how the taxes see it.
There are other rules for various investment types (IRAs, Annuities, 401K), but the basics are as I outlined above. Remember only deal through a broker, and only if he will work your account through a brokerage account (and put his fees in writing). There are too many "investment professionals" who will rob you blind out there if your not careful.
your other option is to do your trading yourself, but I usually suggest people don't do this. talk to a broker at least before you contemplate this option.