If your Manager asked you to prepare business plan for the next year, what's the Basic interlocutor to start in this?

Planning. Just go for meetings and the agenda of meeting is goal setting, in goal setting do SWOT analysis of your business & go with opportunities. make plans. give presentation.

Capacity planning is concerned with determining the level of human and other resources that will be necessary to meet the production targets of the organisation.  It is concerned with establishing the maximum output capability of an organisation in a given time period

There are several ways that organisations can increase capacity.  These include  

creating additional shifts and hiring more employees,  or outsourcing to contractors

getting current staff to work overtime

outsourcing to other organisations

increasing plant and machinery

building up inventory and taking back orders from customers

Before to make a business plan there must be an analysis in the current business trend using raw data like P&L statement, personnel interview and other reports as basis for the plan in the next year business operation. Otherwise without this analysis your business plan is unrealistic and will prone to failure operation (unreachable/ unachievable). Then start to make a plan. The following can be considered as the sequence of the plan: Executive summary, explain the whole thing of the business plan. Company description, explain the basics and style of the plan. Market analysis, explain the marketing strategy. Competition, explain about competitors. Marketing, explain the tools to use to get customers. Management, explain who will manage the operation. Financing, explain how much the budget for whole operation. Then conduct a meeting for the presentation and to get feed back or suggestion from the audience. If its ok approval is a must from the board of directors if any or management,  then implementation.

Arrange for a meeting to facilitate collection of data, study economic out look followed by SOWT analysis then prepare the business plan for the whole business functions of the company (Finance, HR, Logistics, IT, Marketing and Sales) within the company goals, objective and strategic plan.

Then make presentation to get an approval and release to provide each department manager to implement his own area of responsibility.

What do you want the business to achieve in the next year?  OK, how are you going to achieve it?

A business plan may include sections on Legal structure, Product development, Production, IT, Management, Marketing, Sales, Hiring additional staff, Opening new branches, Finance ..... basically, what is each department or division doing now, and what should they do over the next year.