Hi, I’m a long-time Neutral player, I only have one sided character for roleplay reasons and I can say Neutral is still very much a viable alignment to take and comes with some benefits such as aggro-free travel, more quests (can do both sides of some quest lines) and some unique Neutral only items from some raids like Hollow Island. However most people find that the benefits granted by choosing a side are of greater value to them so it’s really up to you.
Since you last played there’ll have been changes to a lot of the nano-programs and there’ll be new areas to explore, take some time to familiarise yourself with the changes if you were used to knowing certain things. For example, NTs, Crats and MPs can all now cast Neuronal Stimulator instead of just NTs among many other changes.
The best way to get experience these days is through daily missions, on Rubi-Ka you can visit either the Omni or Clan agencies to receive a regular daily quest, an elite daily quest and an alien invasion daily quest. You can also approach the bartender in the antiques shop in Borealis for a PvP daily. In the shadowlands you will have access to DOJA chip dailies and when you approach the end-game elite shadowlands dailies.
Once you’ve accomplished your daily quest quota (available from levels 1->220/30) you can do RK dungeons or shadowlands quests to get exp, farming exp from cyborgs on RK or hecklers in SL are also still viable options.
If you want to level even faster you can buy the “New Colonist Bundle” from the steam store page (Listed under DLC for Anarchy Online) this will give you a code you can redeem on your account for a set of luxurious armour that grants a lot of addition % exp and scales with you as you level.
My advice is to take your time with coming back and pace yourself. If you have any other questions please ask, there’s a semi-official discord you can join where the community are extremely helpful and asking in OOC chat channels can be a great way to find answers in game.