Hello Folks. I have four custom pick up fields in Opportunity. Every opportunity has a look up relationship with Campaign. My trigger will loop through all the opportunity records and if any of the custom pick lists is saved with a value 'Completed '  it updates the count in Campaign's custom field. I coded a trigger an it is working perfect. I need help in optimizing this code cause I feel like I have used too many try-catch blocks and also SOQL statements inside  for loops. Thanks in Advance.

trigger Site_visit_update_in_campaign on Opportunity (after insert,after 
    update,after delete) 
{
    public Boolean s1NullCheck=false;
    public Boolean s2NullCheck=false;
    public Boolean s3NullCheck=false;
    Public Boolean s4NullCheck=false;
    List <Campaign> campaigns=[select id from campaign];
    Set<Id> keysForOpp=new Set<Id>();
    Map<Id,List<Opportunity>> oppList=new Map<Id,List<Opportunity>>();
    List<Id> filteredIds=new List<Id>();
    Campaign[] campaign=new Campaign[]{};
    Map<Id,Campaign> campaignToUpdate=new Map<Id,Campaign>([Select Id,Completed_Site_Visit_1__c,Completed_Site_Visit_2__c,Completed_Site_Visit_3__c,Completed_Site_Visit_4__c From campaign]);

    for(Opportunity oppor:Trigger.new)
    {
        for(Campaign c:campaigns)
        {
            keysForOpp.add(c.Id);
        }

        for(Opportunity o:[Select 
       CampaignId,Site_Visit_1__c,Site_Visit_2__c,Site_Visit_3__c,Site_Visit_4__c From Opportunity Where CampaignId=:keysForOpp])
        {

            try
            {
                List<Opportunity> temp=oppList.get(o.CampaignId);
                if(temp==null)
                {
                    oppList.put(o.CampaignId, new List<Opportunity>{o});
                    filteredIds.add(o.CampaignId);
                }
                else
                {
                    temp.add(o);
                }

            }
            catch(NullPointerException e)
            {
                System.debug('Exception at custom Map setting : 
            '+e.getMessage());
            }

        }

        System.debug('opportunity debug'+opplist);

        for(Id i:filteredIds)
        {
             Integer siteVisitOneCounter=0;
             Integer siteVisitTwoCounter=0;
             Integer siteVisitThreeCounter=0;
             Integer siteVisitFourCounter=0;

            for(Opportunity o:oppList.get(i))
            {



                System.debug('Opportunity after calling key : '+o);

                try
                {
                    if(o.Site_Visit_1__c !=null)
                    {
                        s1NullCheck=true;
                        System.debug('S1check : '+s1NullCheck);
                    }
                }
                catch(NullPointerException e)
                {
                    System.debug('Exeeption at siteVisitOne : '+e.getMessage());
                    System.debug('S1check : '+s1NullCheck);
                }

                try
                {
                    if(o.Site_Visit_2__c !=null)
                    {
                        s2NullCheck=true;
                        System.debug('S2check : '+s2NullCheck);
                    }
                }
                catch(NullPointerException e)
                {
                    System.debug('Exeeption at siteVisitOne : '+e.getMessage());
                    System.debug('S2check : '+s2NullCheck);
                }

                try
                {
                    if(o.Site_Visit_3__c !=null)
                    {
                        s3NullCheck=true;
                        System.debug('S3check : '+s3NullCheck);
                    }
                }
                catch(NullPointerException e)
                {
                    System.debug('Exeeption at siteVisitOne : '+e.getMessage());
                    System.debug('S13heck : '+s3NullCheck);
                }

                try
                {
                    if(o.Site_Visit_4__c !=null)
                    {
                        s4NullCheck=true;
                        System.debug('S4check : '+s4NullCheck);
                    }
                }
                catch(NullPointerException e)
                {
                    System.debug('Exeeption at siteVisitOne : '+e.getMessage());
                    System.debug('S4check : '+s4NullCheck);
                }

                if(s1NullCheck==true)
                {   
                   if(o.Site_Visit_1__c=='Completed')
                   {
                       System.debug('Opportunity : '+o.Site_Visit_1__c);
                       siteVisitOneCounter=siteVisitOneCounter+1;

                   }
                   s1NullCheck=false;
                }

                if(s2NullCheck==true)
                {   
                    if(o.Site_Visit_2__c=='Completed')
                    {
                        System.debug('Opportunity : '+o.Site_Visit_2__c);
                        siteVisitTwoCounter=siteVisitTwoCounter+1;

                    }
                    s2NullCheck=false;
                }

                if(s3NullCheck==true)
                {   
                    if(o.Site_Visit_3__c=='Completed')
                    {
                        System.debug('Opportunity : '+o.Site_Visit_3__c);
                        siteVisitThreeCounter=siteVisitThreeCounter+1;

                    }
                    s3NullCheck=false;
                }

                if(s4NullCheck==true)
                {   
                    if(o.Site_Visit_4__c=='Completed')
                    {
                        System.debug('Opportunity : '+o.Site_Visit_4__c);
                        siteVisitFourCounter=siteVisitFourCounter+1;

                    }
                    s4NullCheck=false;
                }

            }

            System.debug('Site Visit One Total : '+siteVisitOneCounter);
            System.debug('Site Visit two Total : '+siteVisitTwoCounter);
            System.debug('Site Visit three Total : '+siteVisitThreeCounter);
            System.debug('Site Visit four Total : '+siteVisitFourCounter);
            Campaign cam=campaignToUpdate.get(i);
            cam.Completed_Site_Visit_1__c=siteVisitOneCounter;
            cam.Completed_Site_Visit_2__c=siteVisitTwoCounter;
            cam.Completed_Site_Visit_3__c=siteVisitThreeCounter;
            cam.Completed_Site_Visit_4__c=siteVisitFourCounter;

            campaign.add(cam);

            try
            {
                update campaign;
                System.debug('Campaign update Success');
            }
            catch(Exception e)
            {
                System.debug('Failed to update campaig : '+e.getMessage());
            }
        }
    }
}