The focused issue on the SAMPREP workshop is introduced. The virtual issue is available at https://journals.iucr.org/special_issues/2025/samprep23/.

Practical advice for preparing samples for use in high-resolution structure determination using cryo-electron microscopy is given.

Shipping of biomacromolecules to synchrotrons, cryoEM and sample-preparation facilities is often overlooked and has the potential to erase months and years of hard work. Here, guidelines and procedures are provided to ensure that samples arrive intact and safely at their destination.

All crystal-based structural biology methods, including X-ray crystallography, serial synchrotron and serial femtosecond crystallography, and electron diffraction, require the preparation of biomolecular crystals. This article covers strategies for careful sample preparation in crystallization experiments to increase the chance of success.