Another way to make gold. This option works well at level 60 when you have some good gear already. Obviously, you should have some gold ready to buy reagents. Be ready for expenses up to 225 skill points in any profession: items below that are not worth much. You will get first income after 225 skill points in Leatherworking, Blacksmithing, Alchemy or Tailoring. Unfortunately, Engineering and Enchanting will still require some investments.  The only way to make gold with enchanting is disenchanting skill (we talked about it).

Only really to expand on Gráinne's comment as regards the 'collecting' and 'roster development' sections - which are, as said 'distinct' although they are intrinsically linked - I would like to point you in the direction of the in-game Achievements > Battle Pets > Collect tab. There are a series of achievements called Raiding With Leashes, pretty much all of which can be completed via the auction house - if you have the gold/inclination - or by completing old raids.