If you have no capital to contribute and you're going prop, most firms -- nowadays -- will bring you in and teach you scalping. Something mechanical and uninformative like stepping in front of size (bids and offers), and holding for very short periods of time, or liquidity trading, which is almost dead. They do this to limit their, and your, risk while forcing you to generate lots of commissions.
They also often make you sign a non-compete agreement, stating that you cannot trade anywhere else for a year or more, lock you into a low payout, and charge you anywhere from .0075 to .01 a share, which no experienced trader would ever pay. They do this because they know most people fail, so they want to lock you down and make sure you make as much money for them as possible before you quit.
Generally their cost basis to cover their fixed clearing costs is .002 per share, depending on how large they are.
Most people after half a year end up doing 30,000 to 50,000 shares a day. So at .01 a share that's $300-$500 a day, without SEC fees, ECN markups, and other charges, which often bring it to $400-$600 a day. After that is deducted from your gross profit, if you ever have anything left over (which is rare), you get a percentage of that at the end of the pay period. Usually you get 50%-70%. The firms keep everything above .002 and their percentage cut as profit for themselves. You cover your own losses.
It is extremely profitable for LLCs to bring in new people to teach them this method, offering nothing beyond that, and then kick them out the door. It's very low risk. After you give them free labor for a year or two you decide if you want to continue once you have begun to understand how the market operates.
This business model makes it very hard for undercapitalized traders to succeed. You have to be very disciplined and intuitive to pick it up enough to survive a few years without digging a huge hole, or you have to have the capital to sit it out for that time and observe, observe, observe.
Only the higher-eschelon prop firms actually teach you something and have a real stake in your success, and they do not regularly recruit without a big process. So just be aware of this now, so that when you sign an agreement you understand precisely what your labor is worth.