There are lots of things that will make or break this... Do you have an intellectual property on your product? Are you sure costumes need/want it?
On the to do list - need to develop marketing material and contact the company you want to license to. Having contacts with the right people/decision makers is very important.
Happy to discuss details of you like.

Develop executable strategy and prioritized action list... The devil is in details of course.
And lots depend on the field and type of business you are trying to build.

I mentor a lot to startups and formal accelerator programs. Glad to discuss if there is an interest.

Most companies these days have people responsible for external innovation and business developement. Somebody with the tittle 'licensing' might also be appropriate. But the key is - never try talking to R&D or marketing people and make sure you have a solid value proposition to offer.
Some times companies have an official portal or form you could submit for their review. If not, using professional intermediary is a better way than to knock the front door.

I guess now is the time to start implementing the plan! What does it say there? :)
Seriously - need to think strategy and go for the missing pieces ... I doubt you need a lawyer or SBA advise to get started.
But the details of course depend on what is it you are trying to do.

Happy to chat if you are interested.

Ha!... Who would give away the big secret?!:)
In my experience the key is to stay in touch and check in periodically, both personally and professionally with your lead contacts. Especially former clients that were happy with your work. Ask them if they could use you again or refer to their colleagues/peers... Stay on the radar also helps but I do it by participating in conferences, presenting and networking. If you are considered an opinion leader in your topic - people will be asking for help and advise.

Another quick advise - always leave extra value "on the table" and be generous in your own referrals....

I'd be happy to discuss other tricks of the trade if you are interested.

I have been mentoring and advising early companies and startups for a while now... It is mostly done through some organizations - alumni or University mentoring services, state or local, or some specialized mentoring groups and services. Most mentors are volunteers and usually they are not allowed to be "compensated" by companies they mentor. Advisors on the other hand are usually compensated for their time (more often with equity and expense reimbursements).

If you do not know an appropriate organization that could help you find mentors and advisers - reach out to relevant experts in your field or academics. People usually are willing to talk and if you like what they are saying you can discuss formal arrangements.

You of course should ask for a compensation that is appropriate to the qualification and your role in the company. In most of the cases a startup can not financially compensate people at the right level - that's why they are offering options and equity to close the gap. The only other way is a deferred payment (they are saying that they will pay you back when they get funding). But equity is the most common way.

Talk to founder(s), CEO and CFO...
There is no 'rule' on how it is done, but the earlier you join, the bigger piece of the action you should be able to claim.

McKinsey publishes a report about 10 key areas that will be disruptive in the next decade... Inc. magazine has a list of others that would be most prolific as startups... So you could check those and a few other resources.

3D printing is there and so driverless cars. Internet of things and medical devices will continue trending...
For some reason renewable energy is no longer a hot topic, as well as 'nano'...

An attitude towards 'failure' is very important and often determines how the society accepts innovation all together... In many successful places failure is like a shevron of experience - and that's how it should be. So you are much better off after your first startup failed.
But if you know that your audience is seeing it differently, then better not to approach them right away. Otherwise you will be caught in discussions 'how is this one is better than that other one'... And this is a waste of time:(

I strongly disagree with the first answer - of course you are building to sell! They key is how fast and what is the multiplication factor for investors...

But back to the question itself, I think the most important thing to remember about investors and fundraising is that you are not just getting money - you are selling your company piece by piece. So at each round you need to be sure that what you get is worth what you give away. Simple math might show that at the end it will not worth much for the founders.
The rest are details of strategy and specific business and need to be discussed directly. Happy to talk.