1. go 29er. its just smoother
2. Avoid ANY makro special
3. Buy a used big brand, like GIANT, scott, silverback.... (Specialised gets too pricey)
4. Cheap bikes are so heavy (like 15kg plus) vs 10-12kg for a big brand bike, that you actually get put off riding, especially up climbs.
5. Should you start enjoying the rough stuff, cheap bands are terrible, steering goes out, cabled brakes or horrible, brake fade. shocks are bad.
6. You want hydraulic brakes, 29inch wheels, tubeless conversion, the right size! super important. Understand the different type of bikes. you get downhill, cross country, trail. whats your intention? Do you want to do a quick blast down the black trails at tokai? or do you want to do a 160km marathon on mostly gravel? (I do both).
7. Stay away from dual suspension as a beginner. reason being, no cheap dual suspension exists. if you cheap out, you will get a 20kg beast thats terrible. hard tail is cheaper, ligther and faster. If you choose to upgrade, then dual sus is king, but a good quality one is exceptionally more money when you try to match the lightness of a hard tail.
Now, you dont need to break the bank! Sure, you can buy new for R2999 at game. but Ill rather save a bit more, and spend R5kish on a used GIANT or Silverback, Merida or even our local company MOMSEN. and if you dont like it, re-sell it for virtually no loss.
I was a Roadie. I then borrowed my boets MTB and fell in love. However i was used to decent tech so i got myself a used full carbon, quality groupset GIANT for R16k (about half price new)... its now 6 years later and i still use it. Good bikes last.
Other things to note:
1) Helmet, you will need one. Goto Chris Willemse, you dont need expensive, you just need quality assured. Its your head after all.
2) gloves, i prefer full finger gloves for the inevitable fall, but up to you. once again. go cheap at first
3) Shoes (and pedals). go flat pedals, and takkies at first. should you eventually want to. cleat up, its way more effecient. but dont ever cleat in as a beginner, you will fall and get terriefied.
4) Shorts. You bum will get sore. but you dont need to dress like a tour de france roadie. get baggy shorts with built in cushioning. and a similar loose fitting cycle top....