For a relationship to be strong and solid there are some things to avoid. No one is perfect in the world most especially when it come to relationship. People are bond to several mistakes and if committed may cause havoc to relationship and life itself. Let look at some of this mistakes to be avoided in a relationship

1.Constant nagging: Avoid nagging, fault finding and frequent sarcastic remarks. For this bring up breakup in a relationship
2.Jealousy: Jealousy can cause great devastation in a relationship and can trigger a breakup.
3.Lying/keeping secret: Lying and keeping secret is also one of the tools that can wreck a relationship. Be truthful and full of fact. Lying can bring about a breakup in a relationship. Some people believe that telling lie and keeping secret will makes relationship grow with the notion that truth will make things worse or end relationship. No! Lying/keeping secret will never build a relationship but destroy it. Keeping secret/lying is a deceit and the more time that passes, the harder it is to fix up. Lying is very dangerous in a relationship for it hurt and bring breakup because it is hard to feel emotionally connected to someone when you find out he/she have kept a secret from you or when you find out the root of the relationship was base on deceit.
4.Regular argument/quarrels: A relationship can breakup if both partners have frequent argument, fight and quarrels most times
5.Love for money: Avoid been money lover. The structure of this is that when a relationship is base solemnly on money, fame, name and influence such relationship doesn’t usually last long because when those entire things go the love dies. Never love someone because of material needs. Money will come and go but love stay. So, when you love someone because of wealth, when the wealth vanishes, the love will vanish. love for someone heart not their material things a good heart is bigger than anything. Avoid been money lover.
number 6-8 will really shock you.read it up at http://www.afrikanviewblog.com/relationship/8-mistakes-to-avoid-in-a-relationship-to-make-it-strong-and-solid/

Why is it always specific numbers? 10 things to do , 6 things you must not do , 11 things that will make him/her love you?

it is specified because writers do bring most important important that we think will benefit. it is very numerous but it is usually summarize to a specific number to make people understand and get the information