Experienced traders usually pick a narrow area of market to become master at. This area of opening gap can be the that small area of the market you may want to consider to be your area. There are many advantages in trading the opening gap. The one advantage is that most of the time your trade is done by 11:00 AM, many times much earlier, and you can have the rest of the day for yourself.
Generally speaking, there is a tendency that market closes the gap at some point. This is called fading a gap. However, this general tendency is not strong enough to justify the risk and reward for any size gap at any day under any market conditions or recent market patterns.
Successful gap traders pick certain gaps under certain conditions that gives them the edge. Just like any other strategy, you want to pick the cream of the crop to trade.
I have studied the opening gaps for quite a while. Using my background in probability and statistics, I have worked on many aspects of opening gaps, starting with the most common aspect that is fading a gap.
In this site, I am starting by sharing data for fading gaps.
The data is going to be presented daily in a table such as following:

Short  Short  Long  Long  Long  
PF  1.54  3.08  1.02  1.33  0.86  
PCT Prof  71%  86%  72%  68%  48%  
Avg Loss  $248  $139  $203  $250  $241  
Net Loss  $11,663  $2,088  $10,350  $4,500  $5,313  
Lose  47  15  51  18  22  
Avg Win  $159  $71  $80  $158  $229  
Net Win  $17,913  $6,425  $10,538  $6,000  $4,588  
Win  113  91  131  38  20  
Avg P/L  $39  $41  $1  $27  $17  
Net  $6,250  $4,338  $188  $1,500  $725  
Total  160  106  182  56  42  
The column labels H, HC, HO, OL, and L at the top refer to a price range relating to yesterday's High, Close, Open and Low as follows:
> H  Higher than High
HC  Between High and Close
CO  Between Close and Open
OL  Between Open and Low
< L  Lower than Low
The numbers under each header represents various information if the market opens at that particular range.
Please note that the labels H, HC, Co, etc. in this example refer to a situation that yesterday's day close was higher than open(Up day). In the case of down day, the labels would be H, HO, OC, CL and L.
The row labels are as follows:
PF  Profit Factor, the sum of all profits divided by the sum of all losses . A profit factor of 1 is a break even.strategy. I personally look for a profit factor of 1.25 and higher.  
PCT Prof  Percent of profitable trades. You can have a high profit factor but a low percent of winning. This will happen if most trades lose but the average win is more than average loss to a point that total win is more than total loss. I am looking for situations that both PF and PCT Prof are high. I look for a minimum of 65% for PCT Prof numbers.  
Avg Loss  Average loss of the losing trades.  
Net Loss  Total loss of the losing trades.  
Lose  Number of losing trades.  
Avg Win  Average winning of the winning trades.  
Net Win  Total winning of the winning trades.  
Win  Number of winning trades.  
Avg P/L  Average Profit or Loss.  
Net  Net amount of Profit or Loss.  
Total  Total number of trades. 
PF and PCT Prof are the two main data values we are looking at in order to make a trading decision.
Here is an example how to use the above guide. Let's assume we are going to make a trading decision based on the above data. First we have to wait until the market is about to open so we can estimate the opening price pretty accurately. Referring to the above table, these are the possible scenarios:
Market opens above the high in H zone  PF = 1.54 and PCT Prof = 71%. These are very good numbers. So we go short at the open.
Market opens in HC zone  PF = 3.08 and PCT Prof = 86%. Cant get much sweeter than this. We go short with increased size contracts.
Market opens in CO zone  PF = 1.02 and PCT Prof = 72%. The profit factor is almost at break even. Although the win rate is decent, the average loss in this zone is much higher than the average win which makes this trade not desirable.
Market opens in OL zone  PF = 1.33 and PCT Prof = 68%. Both PF and PCT Prof are good. So we go long at open.
Market opens below the low in L zone  PF = 0.86 and PCT Prof = 48%. This means that most trades are loser and also the total win is substantially less than total loss. We do not take these trades unless we want to donate our money to the market!!!
As soon as we take any trades, we better place a target and a stop as suggested by the daily guide. The target is simply the gap close point(i.e yesterday's close). The stop is a minimum of 5 points but can vary depending on market true range.
I hope this guide is useful. Please criticize and make suggestions so I can improve it.
Thanks