bit at a loss on gearing

I just finished the campaign and did 2 maps, some heists

now I want to improve my gear, but Im at a loss on the gems...

I have to invest so many many orbs to get the colours right... am I missing something?

cause when i dont get the colours right the item is pretty much worthless.

Or is this normal, that it goes so so slow...

Ive had this problem also during campaign, you get something better but the sockets are all wrong and you have to ditch some skills or supports wich really cripple my build

In general yes, getting the right colours on gear can be a bit of a struggle at the beginning.

Most people prioritize colours and links on gear over stats during the campaign because of that. Meaning they will equip worse gear with the right colours/links over something with better stats but the wrong colours.

Apart from that, u have to know how colouring in PoE works. The stat requirements on an item determine how likely it is to get a certain colour.
For example if u have a Chestplate that requires 180 Strength, u are very likely to get red sockets on that piece, meaning its very hard to get more than 2 or 3 blue/green sockets.
If u want easier colouring in the early game, use some hybrid gear that requires 2 stats to be used, Armour/Evasion for example. There u have good chances for 2 colours and only 1 would be a bit harder.

There's more tips and tricks around colouring, but that should cover the basics :)

This aspect of build planning is one of the things that makes PoE both interesting and challenging.

A tool that can help is the Vorici calculator, which you can find here:
https://siveran.github.io/calc.html

You plug in the total sockets, how many you want of which colors, and the attribute requirements on the gear. It then tells you, ON AVERAGE, how many chromes it will take using various crafts.

It's not unusual to spend a couple of dozen chromes. If the calculator tells you it's going to take several hundred (or several thousand) you might want to think twice.

As Sadaukar suggested, you normally want to choose the attributes of the gear based on the gems you're going to put in it. E.g., if you're doing a build with a lot of green gems, you probably won't want gear that is STR only, INT only, or STR + INT. Or, if you do need something that will hold 3 red gems amd 1 green, be sure to look for a piece of gear that wants both STR and DEX

It can also help to learn how to craft and keep an eye out for bases with certain socket combinations, especially if you're going to need one piece of gear with "off" colors. But, with a little planning, this is not too big an issue for most builds.

Because of these issues, and resistances, it can be really difficult to upgrade one piece of gear at a time. It's better to look at what you have, create a plan, see what else you need to fill it out, and keep an eye out for that gear. Then do a change when your plan comes together.