If it's really your first dive into the oldschool and you started with TIP and you think to continue the journey label by label, I suggest you jump to Dragonfly next. You can pass their first CD since it's very basic and dated 1993 Trance. Same for Blue Room Released, you can safely pass their 1st CD since it's half Techno but I think wouldn't do bad listening it. Next try labels like Flying Rhino. Most of their backcatalogue is downloadable for free from their website, but the real old-skool sound is their 1996/1997 releases; by 1998 they had jumped to Progressive and Housey sound so it's not what you call real old sound. Try also Matsuri 1995 - 1997, by 1998 label had been experimenting in what's not.
Those were my label suggestions. As for compilation series try:
Goa-Head 1 to 7, maybe 8 and 9 later.
Tantrance 1 to 8
Pulse 1 to 6, maybe 7 later
Distance to Goa 1 to 7
Goa Vibes 1 to 3
These are always safe bets.