Strategy is an overused term.
From my perspective, based on complexity theory, any strategy work must be rooted in the knowledge that we can’t predict or control a system’s response to our actions. Given this framing, I am influenced primarily by two perspectives: Strategic Insight and Adaptive & Emergent Strategy.
Regarding Strategic Insight, the seminal work by UCLA Professor Richard Rumelt, who argues that most of what is presented as strategy these days, isn’t. Too often, strategy is confused for vision, goal setting and objectives. He also differentiates between good and bad strategy.
“Good strategy almost always looks this simple and obvious and does not take a thick deck of PowerPoint slides to explain. It does not pop out of some “strategic management” tool, matrix, chart, triangle, or fill-in-the-blanks scheme. Instead, a talented leader identifies the one or two critical issues in the situation — the pivot points that can multiply the effectiveness of effort — and then focuses and concentrates action and resources on them.”
Richard Rumelt, Good Strategy Bad Strategy: the difference and why it matters. 
Strategic insight focuses on recognising patterns, structures, relationships and trends, in order to identify leverage points and actions to move towards an intended outcome.
Adaptive & Emergent Strategy was an area pioneered by Professor Henry Mintzberg, drawing on previous work in ‘adaptive’ or ‘entrepreneurial’ strategy processes, which were distinct from ‘planning’ processes which are by far the greatest in volume and use, despite woeful success rates of the likes of strategic planning. Mintzberg suggests that planning-based strategy is not really strategic thinking, he asserts that strategic thinking is about synthesis, involving intuition and creativity .
Whilst Mintzberg’s work on adaptive and emergent forms of strategy were less prominent in strategy discourse for most of the 30+ years since he published ‘Patterns of Strategy Formulation’ in 1978 , there has been a revival in this practice as the world’s complexity has accelerated, and the effects of strategic planning’s failure have cut deeper into the outcomes for business, government and charity sectors. Importantly, emergent strategy is rooted in observations about complexity.
Recent additions to adaptive and emergent strategy understanding and practice include Sinha & Ventresca’s ‘Keywords: Building a language of systems change’  which articulates the reality of systems change being an emergent activity; Hassan’s ‘Towards a theory of systemic action’  which juxtaposes the folly of predictive approaches to complexity such as strategic planning; Gaziulusoy’s ‘A critical review of approaches available for design and innovation teams’  which found that the existing design and innovation approaches studied were not suitable structural, systemic, societal transformations; Boulton et al’s ‘Embracing Complexity’  which highlights the importance of building a portfolio of concepts, experimenting and adapting; NPC’s ‘Systems Change Guide'  which identifies systems change not as a methodology, but a way of thinking (and being) and an associated ‘good practice’ (not best practice).
I would also highlight the recent contribution of Adrienne Maree Brown’s book, “Emergent Strategy: Shaping Change, Changing Worlds”  which draws on her work as a Sci-Fi Writer and Social & Environmental Justice facilitator & activist, to put forth a blend of complexity principles, social relationality, and a movement-organizing practice based in adaptation. Most books about strategy tend to avoid or ignore the interior condition and belief of those developing the strategy, but Brown dedicates the whole book to constantly intertwining this with the outward-facing action. As I’ve mentioned in the Systems Sight section, the limitation of any interventions in the environmental conservation sector, are related to the pervasiveness of anthropocentric worldviews - so Brown’s focus on personal conditions and social relationships are welcomed . She also indicates a very simple idea - that to harness emergent strategy we need to pay attention to two things: intention and adaptation.
To visualise strategic intent and emergent strategy together, The Social Labs Fieldbook  presents Mintzberg’s explanation in this diagram: