trigger JobTrigger on Job__c (after delete, after insert, after undelete, after update, before delete, before insert, before update)
{
    String errMsg = JobTriggerHandler.OperationManager(trigger.new, trigger.old, trigger.newMap,trigger.oldMap,
                trigger.isBefore,trigger.isAfter,trigger.isInsert,trigger.isUpdate,trigger.isDelete,   trigger.isUndelete,trigger.isExecuting);

    // If error occured, then display it to user
    if (errMsg != null) {
        if (trigger.isInsert || trigger.isUpdate || trigger.isUndelete) { trigger.new[0].addError(errMsg); } else { trigger.old[0].addError(errMsg); }
    }
}

public with sharing class JobTriggerHandler {
     // Main entry point for this handler.
    public static String OperationManager(list<Job__c> newList, list<Job__c> oldList, map<Id, Job__c> newMap,map<Id, Job__c> oldMap,
        boolean isBefore,boolean isAfter, boolean isInsert, boolean isUpdate,boolean isDelete,boolean isUndelete, boolean isExecuting) {
        String errMsg;
        try {
            // Only run a method if previous methods didn't fail
            //As you want to perform operation on before insert and before update
            if (isBefore && (isUpdate || isInsert)  && errMsg == null) {
                // Find hourly rate by calling static method defined below
                errMsg = computeHourlyRate(newList);
            }
            //here you can call any other static methods or some other class method to perform desired operations
            //keep on adding the other logic which needs to be processed through trigger
            //through context variables you can control their execution
        } catch (Exception ex) { 
            errMsg = ex.getMessage() + ' at ' + ex.getLineNumber().format();
        }
        return errMsg;
    }
    
    //Below method will compute hourly rate
    public static String computeHourlyRate(list<Job__c> newList) {
        String errMsg;
        try {
            Set<Id> AccID = new Set<Id>();
            Set<String> JobType = new Set<String>();
            Map<String,Rate_card__c> RateCardMap = new Map<String,Rate_card__c>();
            for (Job__c Job: newList){
                AccID.add(Job.Account__c); 
                JobType.add(Job.Type__c);
            }
            For(Rate_Card__c RateCard : [SELECT Id, Hourly_Rate__c, Account__c, Type__c FROM Rate_card__c  WHERE Account__c IN: AccID]){
                RateCardMap.put(RateCard.Account__c + RateCard.Type__c, RateCard);
            }
            For (Job__c Jobs: newList){
                if(RateCardMap.containsKey(Jobs.Account__c+Jobs.Type__c)){ 
                    Jobs.Hourly_Rate__c = RateCardMap.get(Jobs.Account__c + Jobs.Type__c).Hourly_Rate__c;
                }
            }
        } catch (Exception ex) { errMsg = ex.getMessage(); }
        return errMsg;
    }
}