My max limit is 23000. Is it best to let it fill completely up and then receive shipment?

If it is, should I just get 1 or 2 artifacts and then let it fill back up?

I have been onl;y letting it get to like 4500, but not sure if thats the best strategy or not.

I get them at 263 per hour.

If your cap is 23000 and your income is 263 you probably want to raise your artifact production.

cash in arti points whenever possible is my strat

dont claim if youre under 4k, good prizes start 4k up .. only hold over 20k if youre trying to get mass storage pods

What is good income for artifacts at level 88? I get 4 x research, 2 times credits as I do artifact, but the problem is just finding good artifact planets.

Whats a mass storage pod?

http://galaxylegion.com/wiki/index.php/Artifacts

That has a list of all the artifacts you can get from the drops ("Common Artifacts"). Collect whenever you're above whatever you want costs. A lot of people say above 4000 so you can get Rescued Prisoners. If you know what you want, always collect as long as you have more than it costs, and try to keep it as little above the cost as possible to cut out more expensive artifacts (for example, if you want Rescued Prisoners you want to keep it below 5000 because then you might get a Continuum Beacon, which is a lot of points for something you don't want).