Know the players, their skills-set, preferred formats and conditions
While many players perform across all formats - e.g. Stuart Broad, Chris Gayle, Jacques Kallis - most tend to reserve their best cricket for ideal conditions and format. It is perfectly possible to be the world's best in one format while a non-entity in others.
For example, West Indian all-rounder Kieran Pollard is one of the most valuable T20 players, a regular star at international tournaments and pretty good over 50 overs too. Yet in Tests, Pollard is an abject failure. Alternatively, Australian captain Michael Clarke is one of the best Test and 50 over batsmen in the world, yet ineffectual at T20.
Only the very best can perform well in all conditions. For example, most batsmen from the Indian sub-continent have failed to make the same impact when touring England, Australia and South Africa. The reason is that they learn the game and play mostly on Indian pitches, which tend to be slow, with much lower bounce than encountered in those other countries. Equally for the same reason, English players have rarely produced their very best on sub-continent pitches.
Learn to read how a pitch will play and whether it will deteriorate.
As illustrated above, pitch conditions are pivotal and reading them is one of the keys to successful betting. Arguably, the pace of the pitch, how much help it offers to bowlers and how quickly it deteriorates will have as great an impact on the outcome of a match or an innings total as the players themselves.
Ideally, one should always have an opinion on whether the pitch will favour batsmen or bowlers and which type; how it will be playing later in the day or in Test matches, tomorrow; what the run-rate will be in both the short-term and over the course of the innings and match.
This subject is a constant matter of discussion among commentators, whose expertise in this regard is invaluable while you learn the art, and a useful extra opinion once it has been mastered.
Understand the impact of the weather
Likewise the overhead conditions not only determine whether there is to be play or not, but the nature of the match. If there's plenty of cloud cover, swing bowlers will enjoy a marked advantage and batting totals are likely to be substantially lower than average. If the sun is out, those faster bowlers will receive much less assistance, transferring the advantage to the batsman. However constant sunshine will bake and break up the pitch, favouring spinners later in the game.
An extreme example is Headingley, a ground famous for favouring swing bowling, but that has also seen many scores over 500 in good weather. During the 2009 Ashes series, Australia bowled England out in bowler-friendly overcast conditions on the first day for just 102, before making 445 on the same pitch once the sun came out. This despite England being clearly the better side over the course of the series.
When bad weather causes the number of overs to be reduced in one-day matches, a complex formula known as the Duckworth Lewis method is used to reset batting totals. This can have a huge impact on the match winner market and requires monitoring.
Expect dramatic turnarounds and don't be deterred from taking huge prices
In-running drama is almost a given in this sport, with upsets at huge odds being a regular occurence. In Tests, the draw often trades extremely short before the pitch suddenly deteriorates and teams often fail to chase down supposedly easy targets in all formats.
Equally, the runs total markets regularly see massive upsets. A fairly frequent scenario involves a team losing its last five wickets for less than 50 runs. Alternatively, teams quite regularly hit 70+ runs off the last five overs in T20. In both scenarios, some very short-priced bets will have lost.
Study stats and past results at each ground
Before trading any match, check out past results at the ground in question, using a tool like Stats Guru on www.cricinfo.com. Past trends at virtually every ground will offer useful clues, with regards the match winner, pitch characteristics, innings totals and run-rate. See below for examples.