Marriage is a life-long commitment; hence, it should not be taken lightly. The most important thing to consider is your readiness--be it financially or emotionally. And this readiness not only pertains to you but also to your partner. Both of you should reflect whether you are mature and stable enough to keep this commitment; otherwise, you might end up regretting your decision.
Another thing to consider is your priorities. Being married means prioritizing your family, and when we prioritize things, you may find that there are things that you really need to give up. This often poses problems to couple, as misunderstandings do occur when one makes a huge decision say about career. For instance, you may be offered to work to a foreign country but have to give up the opportunity because this means being physically away from your family.
Moreover, you also need to think about how much you are emotionally mature. When couples build their own home, this is where they get to know each other further. Even though you have been together for the longest time, the impact of marriage is still very different. The quirks and the habits that you find adorable before may irritate you in the long run, because you tend to expect something differently. Hence, it is important to have the patience, love, respect and understanding to get past the both the petty and the serious matters that may cause your marriage to fall apart.
If you don't think you're will not be able to do these, then think things over and talk with your partner about this.