Database building -- 2

I need to create a database of senior decision makers at UK corporate travel agents. The project involves researching the web and making intuitive decisions on the company type to fit the brief. Adding to an excel spreadsheet and then researching the top 5-10 senior contacts at each business, collecting direct email addresses, mailing address and phone number so we can invite these contacts to a seminar. The data collected must be accurate, and entered into the spreadsheet correctly in format and spelling.