Way too many options and some livestock will be dependent on your setup (particularly, flow and lighting).
Easier corals that can stand some nutrients and lower (but not standard fluorescent) lighting are mushrooms, ricordea, zoanthids (zoas), palythoa (palys), xenia, leathers, acans, favias, duncans, euphyllia (frogspawns, torch, hammer, etc.), and chalices. Note that some of the easist corals like shrooms and xenia can grow very quickly and become invasive so be sure you like them before you add them. While some SPS (small polyp stoney) corals are not overly difficult, I would just avoid SPS until later. Also avoid clams, anemones and non-photosynthetic corals as these need a mature tank, typically require strong lighting and in the case of the latter, lots of food and typically temperate conditions.
Typical/reasonable fish options include clowns (percula or occelaris only), smaller blennies, gobies, pygmy angels, basslets/grammas, small warsse, and dartfish. Be sure to research specific fish for compatibility with each other, corals and inverts.
