The basic idea of options is that you think the price is going to be somewhere within a certain period of time and you place a bet saying so. If you bet right, you make money, if you bet wrong, you lose it.
The different strategies give you different ways of targeting prices. For example a call debit spread is essentially "I think the price will be below $X in Y days", an Iron Condor is "I think the price will be between $X and $Y in Z days" and a straddle is "I think the price will move by $X in either direction in Y days".
The different strategies also have different profit/loss curves. For example selling a call option has unlimited loss potential (the stock could theoretically soar 1000x before the option expires) while selling a call spread has defined loss potential.
The process for me is basically find somewhere where the option is typically priced higher than it's worth and sell spreads. Sometimes this is year round, sometimes around earnings.