Percentage market share
Market share estimates help you identify the main competitors in your area. Don't ignore the big competitors - you can learn a lot from them. The '80/20 rule' can help: follow 80 per cent of the direct competitors (companies with the same market share) and 20 per cent of the big players.
Pricing
Find out how your competitors price their products. How competitive is your product in terms of price, quantity and quality?
Their pricing strategies can provide great ideas for A/B testing.
Marketing
What kind of marketing plan does each competitor use? Analyse their websites, their social media strategy. Who do they work with, what events do they sponsor? What is their SEO strategy, taglines and current marketing campaigns? Do they have a referral strategy? An affiliate programme?
Differentiation
What makes your competitors unique and what do they promote as their best qualities? What is their differentiation? Can you identify a market segment that is not yet or only partially occupied by your competitors?
Strengths
Identify what your competitors are good at. How do they work with their customers? What do they include in their reviews? How do they describe the product and its benefits? What kind of advertising do they use and where do they place it? How recognisable is the company (even a small one) to the target audience? Can it be confused with a similar one? Try to test your competitors' products and service chain yourself to see how they work and what they do better.
Drawbacks
Look for problem areas in your competitors' business. Find out what they could do better. This will help you understand your competitive advantage. Is their social media strategy lacking? Do they have an online store? How up to date is their website?
Geographical
Where are they located? Which regions are they interested in? Which part of their business solves online problems? By studying your competitors' geography and customer demographics, you can find out which markets they're most focused on (and if you're lucky, find an area that's not already too saturated with them).