For a quick and dirty commentary:
a) Newbie or not newbie it has no connection whatsoever to the issue.
b) The strong point of powder is its endless freshness as they are powder, after you open the package.
c) In contrast to powder, this is not the story at all with liquid developers, even those ultra concentrated: in theory the do maintain their freshness after you have taken a minor part. But in practice the BIG problem is to find the right container to pour there the exact amount of remaining concentrate. For example if you pour 850 ml in a bottle of 1000 ml, you will be harming the concentrate. Solution: Use a shrinkable bottle of coca cola or whatsoever, but paint it black beforehand. Never buy those accordeon bottles for darkrooms sold at photo stores, they are useless.
d) The weakest point of powder is whenever you want to use less ammounts than those for which you have the written instructions. Amounts of powder are measured by weight. So you will need to buy an accurate weight for tiny ammounts. The results of your processing will depend very much on the accuracy of your weighting instrument.
SO ?
Chemicals are dirty cheap, buy liquid and don't be afraid of throwing away overdated mixtures.
PS
e) In response to a question someone asked in another thread, in my opinion, IT IS IMPERATIVE THAT YOU DECIDE ON A SINGLE BRAND FILM AND A SINGLE DEVELOPER FOR YOUR FIRST 200 ROLLS. Once you dominate that film and that developer, using other films and other developers will be a kids play.
But if you jump from developer to developer and from film to film you will be chasing your own tail for life, or until you become fed up.
f) As a general rule Kodak company is extremely lousy in their recommended times. In contrast Ilford is very accurate. Therefore Tri-X film with Ilford chemicals is a winning combo.
Cheers,
Ruben
PS II.
Gals & Guys - processing is very much like cooking, each one with his/her modalities and experiences. So I am not going to argue with anyone.
But the only difference between cooking and processing is that you cook in a kitchen, but procces in a Darkroom, which is very often called in other countries LABORATORY.
Why "laboratory"? Because you MUST assure conditions that allow you to REPEAT exactly what you have already done, or shift away by will, in ACCURATE measures.