The best advice (given above) is to stop trading if you don't know how, since there is a great potential to lose a lot of money.
Good advice that has already been given:
% gain or loss is the only thing that matters. You should size your orders according to the amount of money you're willing to risk on a particular trade (share price isn't really a factor).
Your question implies that you're trying to employ a buy and hold strategy but you're asking about day trading. This alone might indicate that you need to do more research first.
Investing is a grind. You will not get rich right away if you're doing it right, but you may produce some good income. The amount of income you can make depends directly on the amount of money you have. Trading equity probably isn't worth it unless you can trade $5000 weekly or so, given the amount of time you will spend worrying and commissions paid. If you trade this amount of money skillfully, you can probably consistently end each month with 30-50 more dollars when you're starting out. This translates to a roughly 7-10% rate of return, which is likely better than a bank will give you and more than you can expect from buy and hold in an average year. The downside is it requires work. When I started day trading, I treated it as a part time job and made about $10/hr. I think this is a healthy way of thinking.
I disagree with previous answers that say investing is necessarily zero-sum. Traders use many different strategies on many different timeframes.
At the scale you can work at as a human, high frequency trading isn't very visible most of the time, and buy-and-hold may expose you to too much external risk that a fund manager is more prepared to ride out. Helping someone exit from a riskier bet that still has a little profit left helps everyone. Selling into a trend when you've made your target might allow an employee to get his stock bonus shares. Think of it more like a garage sale.
My advice is this if you still intend to do it:
First off, consider who is paying you and why. Nobody is going to give you money for free. In the abstract people pay day traders for the service of providing liquidity to distressed shares. A share price declines from its peak and they want to exit to preserve their longer term profits. A share prices has become too low and could use a spark of purchasing to start a rally. Your job is to give somebody the exit they want at a fair price, determined by market orders or to reward employees who are slogging along during periods of low prices. This is what you get paid for.
You will absorb losses from time to time, but more often, assuming you do your homework, you will get a share at a slightly lower than consensus price and be able to exit it at a slightly higher price. As such, you must learn to conquer fear and buy shares whose prices have declined recently, and may still be declining. You can do this confidently by determining a logical basis for having a higher share price based on historical ratios for the company and industry. Additionally, you must set an exit price target and timing for yourself and conquer greed by selling a share that has risen or may still be rising.
It's worth reiterating that you must enter ownership at a low price and exit it at a higher price. The amount of time you own a share represents risk because you are diversifying along the time axis rather than across companies. You must conquer fear and greed to at least a small degree to trade well.
Share prices follow cycles that alternate below the consensus price and above the consensus price on varying time scales, and these are semi-predictable. If you day trade, you will likely become comfortable with one time scale and a few strategies you are prepared to evaluate and employ over and over.
I started trading by just sitting down to my new scotttrade account, believing that a share price was too low and buying a bit of it, exiting when I felt good about getting a little money. You can start simply if you're willing to learn.