Sales and marketing will always be natural partners and their common relationship is your brand. But their mandates are quite different, therefore, it's important we clearly define each department's responsibilities.
Working together is important, but independence is also important. If you have sales and marketing reporting to the same department you have to be careful one isn't ignored. If that happens (like focusing on sales only for 6 months), you will soon find that you have been compromising the long-term prosperity of your company. Don't fall into that trap.
To help you easily analyze your businesses, I recommend you break a customer interaction into 5 parts and identify responsibility. Here are my recommendations to start your discussion.

Customer Interaction
Prospecting (identifying, sifting and sorting)
Conversion (raising demand and lowering prospective client barriers / building trust)
Creating a unique buying experience
Sales… with support from Marketing
Saying thank you
Marketing… with support from Sales
Retention / communication (back to the top of the funnel)

Sounds simple? It can be, but many companies do get bogged down because of confusion about who is responsible.
The next easy step to increase sales is to hold brainstorming sessions - and you may need more than one. For example, hold one session about how to introduce potential customers to your products/services and another about how to deepen existing customer relationships. Do not include multiple objectives in a brainstorming session.
Follow these simple steps and I'm sure that soon after your brainstorming session you'll soon be building smart, cohesive marketing plans that will fill your sales funnel and increase the revenue you generate.