***NOTE*** This is just my opinion, and my suggestions based on past experienced. If any server names/sources are named, it is for example purposes, not advertising purposes.
Since this is my opinion, I do not intend any flame, hate, or advertisement.
~~ Donator Benefits.
What kind of benefits will donators have? Something like this should probably be planned ahead of time; so that you know what to code for, and so that people can know what they may or may not be donating for ahead of time.
~~ Hype
Create Hype. Use Youtube, make a promotional video, spread the word. Get some anticipation going.
~~ Beta Testers
Let 4-5 trusted individuals in early, so that the server can be properly Beta Tested. It would be better to find out early- before the server is released- that if you drink a dose of prayer potion and then a rocktail you'll be healed to max HP. You can also test for balance issues, which is a common problem I see with 614+ sources. It seems people are too happy on the AGS, because in Legacy (And many other 614 sources) the Armadyl Godsword is super overpowered. Everything that happens should be documented, (Hypercam, Camstudio, etc.) So that you can go back and look for issues. (If any exist)
~~ Nex
Make Nex as similar to the Nex on RS as possible. The problem with lots of RSPS's, is that they make Bosses and Monsters simply too easy. For example; On the server that I administrate- Rune-Xile (Which I will probably leave as soon as this server is released)- The Hybrid PVP Source they use had the majority of the drops missing. The only "Boss" that dropped anything was KBD, which is just too easy. The drop rate was also way too high.
DO NOT LET THAT HAPPEN. Make Torva/Pernix/Virtus (If you code Nex to drop them) Make sure that it does not drop them too often, does not respawn too quickly, etc.
~~Voting
Give people something for donating. Be it points towards a rare, anything to get people to vote. The Big servers all give something for voting. Tokens, Cash, Points, anything to give some extra incentive toward voting.
~~Rares/Spawn Economy
Create an economy. Make certain things unspawnable, and can only be dropped via Bosses. Bandos, Godswords, etc. Anything to create an economy, with that care-free feel for those that just want to PK, but the economy for those that want to be big and rich, and have the thrill of that large stake fight, or that infamous ags pk.
~~Staking
Staking is a large part of an economy, and a powerful- and addicting- thing. This ties in with Beta Testing. Make sure Staking is 100% coded, and there are no exploits to speak of. Another downside to Rune-Xile- If you had Food turned off, you could still eat if you had rocktails, and there were numerous other large exploits.
That's all I have for now, I might think of something else.