Weight is personal. I have recently started training with my early pubescent son so his max weight is currently 2 x 1.25kg disks tied onto a piece of plastic plumbing pipe, my 10 rep max weight is a touch higher than this, but I've got 23 years more experience than he has.
There are ways to increase intensity with lesser loads, which is not a bad idea in early stages, more weight does equal more risk, people saying otherwise are idiots. The important part is to have done your rep max. If you finish a set of 10 feeling like it was easy you didn't push enough. If there was 1 more or even 2 in you in the early stages that's not too bad, by the time you are a more 'seasoned' trainer this becomes less acceptable. When I rerack after a set of squats I am either finished or thinking up the weight next time.
To increase intensity without increasing weight you can do some or all of the below.
Add impact, if safe. My heaviest ever squat is 205kg, heaviest ever jump squat is 100kg. Getting an inch or so of air beneath my feet halved my potential lifting ability, strictly speaking it didn't as I only did 205 for 1 and managed 100 for 6 but the principal is sound. Use this method with caution, if there are injuries etc. that could be aggravated by impact, don't do it until you are sure and if you do ensure there is someone there to keep an eye on your form, someone who will not be afraid to tell you if you're doing it wrong, my son is great at this.
Remove rest. Circuit training is a way of being able to decrease your max weight needs. You have a session where you go from one exercise to another with no rest, 10 reps of each, this can be whole body if wanted. You recover from one thing while doing another, but overall fatigue will win out and even if set 1 felt easy enough to add a bit more weight I guarantee you set 3 or 4 won't. Have water nearby, you will get very warm and need it.
Expand range or slow movement. I will come to pace later but slowing the movement down or expanding the range of movement under control are valid ways of making the weight feel heavier. As a bit of fun I decided to do slow rep work at the end of last year, a single deadlift was taking me between 20 and 30 seconds making my entire body shake like a leaf well before rep 10. Range extension is good if not bounced etc. I have seen people boast of doing butt on heals squats and seen they are bouncing off their heels to give them momentum, making it easier, control is key.
The speed debate. Is slower or faster better? Yes.
Slower movement means you are under load longer making the overall intensity higher. However a fast movement requires co-ordination and control to do well so per moment it can be more intense. Consider the idea of someone doing push ups for a minute without any pause or rest, someone doing 10 means they have taken 3 seconds lowering their body than another 3 raising it without stopping at any point, this is intense. Another person doing 50 will have taken barely more than a second per rep so worked hard and fast throughout, not the soft option.
Pace is something to play with, but in early days stick to moderate, slightly slower or faster. As you become more experienced it can be fun to push yourself in both directions.
Something I call fast reps is in a way a bit of a misnomer and should only be tried after consultation with a psychiatrist. The principal is to try lifting the weight as fast as possible then controlling it back down. The crease in this sensible seeming session is the weight is more than I can move fast, so in effect I can spend a few seconds trying in vane to move a weight in a hurry, this increases the intensity immensely. You need to be very confident in the movement to be doing this and ideally have a spotter, rep failure rate on this session is high.
Faster can be more dangerous if done badly, but so can slower. Being in a dodgy position for a long time is no safer than being there for a moment. It is easier to do fast movements dangerously because people concentrate more on pace than form. I tend to say get the form 100% first then play. If you are in doubt have someone watch you. There is nothing wrong with doing something safely wrong, low intensity, and learning from it, but dangerously wrong is stupid. I post up some videos of me doing deadlifts with fat gripz some over a year ago because I knew I was getting them wrong. I got torn apart by some of the regulars here for various errors, most I had spotted myself, but the net result is I can now use this new kit as part of an exercise I am very used to safely. Others sometimes post videos to boast, I only put up the rubbish stuff. People who will tell you what you are doing wrong based on your own criteria are invaluable.
Be careful on intensity in early stages. If you find yourself immobile too often it can be hard to keep motivated. I'm just moving out of some remedial work so when I was walking like I'd soiled myself last week I was happy about it, we fitness fanatics are a strange bunch. Strangely as time goes on you either become happy as you are and stop aching nearly as much or keep finding new and creative ways to make sure you tell the day of the week by which body parts hurt most.
The main part people forget when declaring as you did 'I do want to build muscle tone' is that it has to be built. No muscle can't be toned, there has to be something to carry the tone. As another poster on here, goldfish, often points out women building muscle is generally incredibly slow, there are heavyweight body builders who have injected testosterone into their bodies to make them more male in how they gain muscle, others who are genetically gifted to gain weight more easily. But on the whole if you trained like a body builder when doing your weights and still keep to aerobics etc. the reality is you will build up a small amount and just look toned. The standard fear of many women is to look too bulky and muscular, truth is most women would have to work incredibly hard for years deliberately to do so.
Most amusing thing I remember hearing was a woman who'd come into the gym with her friend and, while her friend trained she sat in the lounge. Her declaration of 'I wouldn't want to do this weight training because I wouldn't want to get big arms' would have been less amusing if she wasn't sporting a set of minimum 15 inch arms, looking over twice as big as her friend in the gym's. Big difference of course being hers were pure blubber while her friends were mostly lean muscle that looked smooth and toned at rest and more serious under load.
Main thing I forgot last time. Make sure you find stuff you enjoy. If doing what I say is horrible for you and you hate it after giving it time to grow on you, stop and find something else, even come back and tell us here so we can suggest alternatives. If you find stuff you enjoy that gets the gains you want at half the pace of stuff you hate, take twice as long. Most people quit training because they don't enjoy it rather than because they see no improvement. Early gains happen quickly but if you hate what you are doing the slower gains that happen the rest of the time won't seem worth it.
My brother plays football and hates weight training I am the opposite. Subsequently he plays football, I do weights, both of us have done for many years because we enjoy it. We both enjoy cardio of different types so despite both being middle aged and him drinking like a fish without gills the chances are our hearts are in good shape.