*No attorney can guarantee the enforceability of a prenuptial agreement.*
Some factors that increase the chances of enforceability are:
(1) Time: Giving the spouse that is not asking for the prenuptial agreement more time to consider the agreement. If possible, this should be done before an engagement. If that is not possible, then as closely after as possible. The more time the spouse not asking for the prenuptial agreement has, the less the agreement looks like it may have been made under duress. After the invitations have been sent out and deposits have been paid, sometimes embarrassment and financial concerns of the risk of the wedding proceeding can constitute sufficient duress to void a prenuptial contract. All things considered however, contracts that were given to the non-requesting party only days before the wedding have been upheld. However, this is not the best practice and decreases likelihood of enforcement immensely.
(2) Negotiation: If the other spouse has time to negotiate more favorable terms and actually does negotiate more favorable terms, the agreement is more likely to be enforced.
(3) Representation: If the other party has representation, the other party is more likely to understand the repercussions of the agreement, and therefore the agreement is more likely to be enforced.