Gil and Jeanne Team Composition

If you want to maximize gils potential , raise him to his max and try to team up him with another buster servant and a support servant , don't mix gil with Jeanne because his endurance is quite enough to not need a tanker..
As for your jeanne .. Try to team her up with ur uncle vlad and then mashu (I'd rather build this team than gil that only depends on affinity) with a zerker+ruler+shielder = anti affinity(immortal army) , plus this is an Arts spam team , you can either abuse the arts meta for stalling or for spamming arts np.

Standard way to maximize Gil's effectiveness for new/f2p players who have him would be Gil, Hans, and a support Waver. Basic idea being use arts chains to get NP for gil to NP spam with while Hans supplements Gils own already solid star generation(Brave chains will net around 20 stars). I assume you're using Jeanne to fill a similar role to what Hans would normally do but the problem with that is that she steals more stars than Hans does due to her ruler class having a high star weight and she also lacks a crit buff for supporting Gil.

Jeanne on the other hand is a bit of an odd ball servant in that she has the very specific job of being an anti servant tank which is not a role that comes up a huge amount of the time, however when you do need it she fills an invaluable niche as for teammates you can really just throw her with anyone with arts cards and she'll do okay. In her case she really can't wait to get her NP upgrade so that the stun is removed to reach her full potential though.

For gil pair him with shakespeare. Buster up np gain and star gen up. For jeanne, vlad as dps and tamamo as support. Mozart is recommended for free support. Arts up and stars.
Edit: wait, how new are you cuz i see artoria lily..