Hiya Sprint, I can help you with this.
What is the wall you are rendering made of, and what condition is it in?

Old brick walls with cracks etc. need to be covered with expanding metal first, which gives the rendered layer a separate 'base' to reduce future cracking.

If you are going over timber walls, then the expanding metal layer is an imperative.

Cement sheet or good brick walls  do not need the mesh layer, and good preparation of the surfaces by cleaning, and applying a bonding agent is all you  need.

Bondcrete was what was used in the old days, but now they have a greater range of products, which have different strengths, in different circumstances.

So wash your wall down very well, if the weather is warm then try and keep the surface damp, if it is too dry it will suck the moisture from your mix too fast, and reduce workability and adhesion.

Your mix can vary a little depending on where it is going, but a 6 to 1 ratio of 'sharp'(washed plasterers sand), to cement, plus between a half to single measure of limil, is your 'standard' mix.

You can add some 'elasticiser' to the mix, but it is not usually necessary.

You can apply about a 5% to 10% strength bondcrete mix to your damp wall just before applying, and you can add a few caps of bondcrete to your mix as well, for a little extra adhesion, if you need it.

Preparing the wall with battens, or some flat headed clouts, at intervals to give you level points to work to is a good way to get a smooth plumb(vertically level) surface, it all depends on how "perfect" you want to make it look, some like a more rustic look, and some want it like glass.

Experiment with your mix for the right consistency, too wet, and it will 'slump'(run down like a curtain effect), and too dry, and it will be crumbly, and won't stick properly.


So lay plastic along along the base of the wall to catch waste and then use a 'hawk' ( a square board, about 400 mm square, with a handle out the bottom that you load up with mix that you hold against the wall) and a steel float/trowel, which you use to push the mix onto the wall.
Push onto the wall, then push upwards with a turn to the right to finish off.

This is when you will find out if your mix is the right consistency to actually 'stick' to the wall, if too wet add a little more prepared dry mix to the batch, or too dry some water.

Once you have it applied, then use a straight edge to screed it flat, which is why you have the clouts or battens to work to, to find your level.

Aim to get it right in at least two coats, but possibly three.
Feel free to whim me if you want more help.