Firstly, DON'T buy the cheapest (on the reasoning that 'Oh, well; if I don't like them, then I've not lost much), because it is much more likely that you won't like them than a better quality pair, and we wouldn't want a new wearer to fall at the first hurdle, would we? I would suggest a good-value middle range style, such as Doyeah 0838 or 0858, ComfiLon 549/535/577, which are all excellent first-time buys, along with the Collanto LegSupport range, the Aries Goldwear support style, or if you want to start with opaques, ComfiLon 849/839/857, LE D500's, or either of the Lida or Collanto or Aries Goldwear opaques.
I would definitely NOT recommend you start with the low-to-no Lycra models, as they are not representative of the comfort, durability or general quality of almost any other style we carry; we wouldn't want a new wearer to be put off by these (unrepresentative) styles. If you fancy trying them after some of the other, better quality styles, then fair enough; just don't start with them! The same applies to the Collanto Adam cotton opaques, which are more like socks that happen to go up to the waist than tights; save them till after you've tried their own Aurel 40 or 70 styles (or any of the opaques recommended in the previous paragraph), which are much better in almost every way.
You may be wondering why I haven't mentioned the premium models, such as Gerbe, or ComfiLon 599's, any of which would make excellent first-time purchases for the aspiring newbie; I just don't want to be accused of 'pushing' the most expensive styles on the unsuspecting new boy! But you certainly do get what you pay for - the Gerbe styles and the 599's are all awesome in terms of comfort, and also surprisingly durable too, so if you can afford them, go for it; you won't be sorry!