Good question. I should write an ebook on that once ;) It's a lot of little things though. A few major ones that come to mind: Learn to scan entire code bases

Good question. I should write an ebook on that once ;) It's a lot of little things though. A few major ones that come to mind: Learn to scan entire code bases (+docs/wikis) to get a solid high-level overview of the entire system and fairly in-depth view of the parts under active development in at most a few days. Basically cram like you would for a last minute university exam. Blend in fully with current culture and process. If you choose not to, make sure you know the costs of change and do so only if you can decisively implement the change and have it deliver a net positive effect during your stay (hardest skill of all.) Quickly establish trust in your technical competence without being perceived as showing off. Usually jumping in to help fix bugs, giving colleagues 'aha-moments' and identifying (elusively obvious) fundamentals work well for me. Grab every opportunity you can to figure out what someone does and show them you're a good guy/girl, whether at lunch, in the elevator or even just in the hallway I call it 'collecting pointers into the organization.' TL;DR Work your ass off at the start to consciously do in a few weeks what normally happens by osmosis in a couple of months.