This is my first grow ever! Any tips for beginners...

After you’ve planted your seeds or rooted your clones, it’s time to get them growing. Lower your reflector so that it’s closer to the plants rather than making them stretch to reach for light. Raise the lighting system as your plants grow. Set your light timer to be on for 18 hours per day and off for 6 hours. During this vegetative stage, the plant will grow leaves and branches but no flowers (unless it’s an auto-flowering plant). Avoid overfeeding and overwatering your plants at all costs. Err on the side of caution as it’s always easier to add more nutrients or water than it is to take them away. Marijuana roots prefer a wet/dry cycle so lift up your buckets and you’ll get a better idea for if they need watering or not by the weight. The first sign of overfed plants is burnt leaf tips.

Don't over water, it's the most common newbie mistake, leer the soil dry between waterings. Second, don't feed if there's no signs of deficiency, let the soil feed the plant

Hey I saw the yellowing tips you mention, my seedling did this when I tried to put her on 24 hours light and it happened quickly, some of us would advise a 20 or 18hr light schedule, unless 24 is working well now. If you can add a cup on top or bottle for a cheap humidity dome they love moisture at this stage. I also see your night temp is fairly close to the day temps, if you're giving any sort of night, try to cool down by 5-10 degrees probably just a small fan would do it. Go easy on nutes this early on the plants will be happy and your billfold too. Any extra lights you can add cfl or other especially during flowering to boost above the 100watts would probably help out also. From what I understand many small lights are better than just 1- 2 strong ones. Happy growing.

Overwatering is the most common mistake made by beginners. Give your soil a chance to dry out a little before watering again. Also, if you’re not monitoring ph, it’s money well spent to check and adjust ph. I resisted ph at first and it was not a smart thing to do. My plants are doing much better since I’ve started adjusting ph. But most important... Have fun!