Best practice and advices making openly available scholarly publications and data:
Preprints services / publication repositories
The use of preprints servers should be OK with most Planetary Science-related journals. More general infos are e.g. on wikipedia
Arxiv
Open Access journals
Open Access journals welcoming Planetary (Geo)Science content include:
Planetary journal-specific recommendations
Elsevier (Icarus / PSS / EPSL)
excerpt from Elsevier preprint info:
Authors can share their preprint anywhere at any time. If accepted for publication, we encourage authors to link from the preprint to their formal publication via its Digital Object Identifier (DOI). Millions of researchers have access to the formal publications on ScienceDirect, and so links will help your users to find, access, cite, and use the best available version.Authors can update their preprints on arXiv or RePEc with their accepted manuscript
Journal of Geophysical Research (Planets)
excerpt from AGU publication policy
AGU does allow posting of preprints and accepted papers in not-for-profit preprint servers that are designed to facilitate community engagement and discovery across the sciences
Useful Tools and scripts/robots
EU H2020 specific OA info
excerpt from section 2.2.1 of EU H2020 open access document
Open Access archives, so called repositories, may be institution-based or subject-based collections like the economics repository RePEc (Research Papersin Economics) or the physics repository, arXiv
An interesting tool produced by PeerJ is paper-now